Miu Fūrinji is a young teenage girl of average height. She has fair skin with a beauty-mark under her left eye, bright blue eyes, and long straight-blond hair reaching down to her hips with short bangs. Normally, she styles her hair to allow a few strands of hair to form a thick antenna-like strand hanging in front of her face. While constantly considered very cute and attractive, her most noticeable physical trait is her slender yet surprisingly developed and curvaceous-frame for a young girl, especially her well-endowed breasts. She also sports slim waist with flared hips, and a lean yet well-defined build.
Initially she would wear non-corrective glasses and braid her hair at school with her school uniform, but later when Chikage accuses her for not being true to herself, Miu discards her glasses and let her hair, including her bangs, to flow freely. When at home, she is usually seen in a purple-spandex outift and other various articles of clothing (including a yellow apron) or a sweater over her outfit, though the spandex outfit is almost always destroyed during any fight she is in. She also constantly wears two red hair-clips, one that flips to reveal a small blade and the other a lockpick, which were gifts from her mother. While not at school wearing her school uniform or her pink gymnastics outfit for gymnastics class, for casual wear, she tipically wears dresses or simple tops or blouses with skirts (despite her stating she doesn't really like skirts due to how they get in the way of fighting).
When brainwashed into Bulu, her hair becomes rather unruly and her eyes are emotionless. During this time, she wears a light blue, one-piece Tidat outfit, without any undergarments along with a light hat and leg guards, while the feet are left bare. The outfit is completed by a bird mask with a long beak and feathers on top to conceal her face.
Despite her arduous past and her numerous chores, Miu has constantly shown herself to be a very kind-hearted, cheerful, gentle, polite and upbeat individual, constantly caring for other people and helping in their needs. Unfortunately in contrast to her gentle nature, Miu’s intense training from her grandfather has conditioned her to by instinct throw people who sneak up behind her; a trait that her grandfather claims to be unintentional on her part, which is something of a running gag of the series.
She is arguably the only one who worries about Ryōzanpaku's financial situation She can become quite fierce when monetary issues are brought up (so much so that her own grandfather was afraid of the idea of her finding out he spent 100,000 yen). When her fears are finally realized and Ryōzanpaku becomes bankrupt, she becomes determined to push the masters to teach little children in an attempt to gain some income, even intimidating Sakaki into helping despite his protest he doesn't teach kids. Miu's worries about finances can, at times, come across as being greedy; shamelessly asking Kenichi to sell the gold medals he received from defeating YOMI members, being flabbergasted at Akisame's refusal to sell a statue he carved for a high sum of money and immediately deciding to pilfer Rimi's pure gold shoes after defeating her, considering them the "spoils of war" (which Thor notes is the same reasoning as that of a thief).
Also, despite her many positive traits, she has low self-esteem when it comes to social interaction. Growing up with never making any friends, due to her constant traveling and training with her grandfather, Miu initially felt nervous in meeting people. In her previous school, all the other girls were jealous of her high grades, athletic ability, and especially her looks. It is because of this that Miu attempted to moderate her appearance by fashioning her hair into a plain-looking braid and began to wear glasses. Though she eventually discarded them after attempting to convince Chikage to be true to herself only for Chikage to accuse Miu of not being true to herself as well, as Miu now appears without her plain-looking self to her beautiful true self. After meeting Kenichi however, she manages to make quite a few friends over the course of the series due to her kind nature and some help from Kenichi.
Despite being very intelligent in in school and martial arts, Miu has shown a bit of a niave and thoughtless side, such as in certain situations, she notices minor things despite how serious the situation is. Such as when she and Kenichi were on Diego Carlo's ship and there was a bomb, Miu just noted how pretty the view from the ship. Possibly due to her grandfathers continuous training since she was little, her constant travels and life-threatening situations keeping her from doing normal things a child would do, Miu has a very childlike personality when it comes to events that she's always wanted to do. Thor has noted she gave up a lot for the sake of martial arts and missing out on several fun activities, as one of them she's always wanted to do is ride a merry-go-round. Her childishness is shown when she went to the aquarium for the first time, she completely forgot she was supposed to look for Kenichi and instead focused on all the fish and acted very excited and childish. This is also shown in regards to romance, as she noticed how Ukita, Kisara and Freya were in a "love Triangle" as she puts it and acts very energetic in regards to romance or people in a relationship. However, she herself is very flustered and shy when it comes to her romance life and her feelings for Kenichi.
Like Kisara, Miu loves cats such as playing with Renka's hair as it makes her look like a cat and wears the badge of a cat that Kenichi gave her when they were little. She constantly plays with cats any chance she can get and acts in a very silly and lovable manner towards any kind of cats or people with cat like feature, which tends to be a running gag of the series, especially with Renka's hair. Her love for cat goes overbroad went she is feeling lonely (because Kenichi isn't there)
Despite her kind and friendly nature towards others, when angered, Miu is surprisingly terrifying, which is usually caused from her Dou Ki fighting style. Such as whenever her friends are hurt, Miu enters a berserker mode and can't seem to control herself, such as when Sho hurt her friends or when Jenazad tricked Hongo into almost killing Kenichi, Miu loses control of her emotions and attacks in blind rage. Words don't seem to reach her and only by incapacitating her or, as shown with Kenichi, groping her breasts seem to help her regain her senses. Junazard used this to his advantage to brainwash her to make her his new disciple by turning her into a mindless killing machine he calls Bulu. However, when Kenichi brought her back to her senses through his willpower and determination, she was able to break out of Junazard's spell and finally return to normal. Kenichi refers this side of her as "her other personality" that comes out when she loses control of herself. Kenichi noted Miu fears this side of her and tries to supress it due to her fear of hurting someone.
Miu truly treasures the friendships she has made, especially with Kenichi greatly, but seems oblivious to his true feelings for her. She has however, repeatedly hinted towards deeper feelings for him, such as getting embarrassed and flustered when they are called a couple, not being able to understand the relief she feels when Kenichi refuses to go to China with Renka and perhaps most famously, becoming jealous and rather possessive of him whenever another girl shows affection for him. She was also very happy and blushed when she heard Kenichi talk about how much he cares for her. After Kenichi saves her life on the school ski trip, she becomes much more open and physically receptive with him, going as far as to tearfully hug and thank him for saving her and staying alive. Every time Kenichi is left severly injured or returns even safely from a dangerous mission, she's always hugging him admitting how glad she is that he's alright. By the time of Miu being left alone with Kenichi for a while when the masters were missing, in addition to starting to realize Kenichi feelings for her, she appears to have started realizing her own feelings for him, going as far as kissing him on the cheek. While they didn't get to discuss the matter any further, several people at school have since noticed Miu being more cheerful and energetic, as well as as more eager to be around Kenichi. As stated by Junazard's observations of her around him even under his control, Miu's feelings for Kenichi have developed even further and has fallen in love with Kenichi (though Miu doesn't seem to be aware since she was brainwashed at the time). Miu has even stated she does not mind dying for Kenichi so he can live and placed his hand on her heart stating she has the utmost faith in his ability to protect her.
Hayato is Miu's grandfather, and, like any granddaughter, she loves her grandfather very much. Hayato has raised her since she was found in the snow by her mother and has raised her in martial arts since that day. However, due to his influence on her has caused her to have gianed very sharp reflexes that she will throw anyone who sneaks up on her. Miu is also annoyed by her grandfathers tenacities to buy expensive scrolls without her knowledge and waste money from time to time. Hayato also possesses a soft spot for Miu, stating that for anyone to ever marry her would have to first defeat him in battle. He even once threatened to kill a man who was holding her hostage despite being a devoted follower of Katsujinken. He loves his granddaughter very much and worries over her well being when she's hurt or in danger, such as when she was going on the ski trip with her school, Hayato was worried about her panicking about how her mother died in the snow. He was also worried about telling her about her past with Saiga, wondering how she would react with how her father abandoned her and her dying mother. When Miu was taken by Jenazad, Hayato only blamed himself for this and became desperate in his search for her, such as traveling all over the globe in his search for her while angrily shouting out for Jenazads name. When Miu was safe he became mad at Kenichi for holding Miu in his arms then became very happy that she was safe with tears of joy that Kenichi had protected her.
Saiga is Miu's father. No interaction has been seen between the two. It is strongly implied Saiga is responsible for killing Shizuha, Miu's mother while the latter was just a baby and has caused Miu to develop trauma's in blizzards. However, Miu is constantly trying to figure out more of her history and who her father is since she's known nothing about her parents since she was little and Hayato doesn't want to tell her everything till she's ready. However, Saiga has shown that he does care for his daughter's well-being, such as helping Sakaki and Kenichi (while disguised as John) find her and protected her from Jenazad's men and even thanked Kenichi for protecting her so well. He said he would only intervene if Miu was ever truely in trouble and has always been watching over her.
Shizuha is Miu's mother. Shizuha deeply loved her daughter very much and even said how cute she was before she left her to protect her from getting killed presumably by Saiga. Miu deeply misses her mother and, due to her death, has caused her to develop trauma's in blizzards.
Miu fairly gets along with Sakaki due to him being the most "normal" master of Ryozanpaku and how he treats Kenichi. However, when he refuses to do something for her, she can act very intimidating and even cause someone as stern as him to cave in to do what she wants. She also grows upset whenever he lashes out at Kenichi from when he was recovering from Kokin and told him to go easy on him. Sakaki also cares a great deal for Miu, going as far as to go to Tidat to save her with Kenichi and was relieved to see her alright and out of Jenazad's control.
Miu gets along well with Akisame due to his calmness and being one of the more mature masters. Though she will be rather scared of the machines he forces Kenichi to go through. Akisame was also willing to help Miu prepare for the play she's been wanting to play for a while. She was even worried when she saw him losing his calm nature from seeing Ogata's treatment towards Ryuto.
Miu, like Shigure, does not get along with Kensei due to his perverted nature and how he's constantly trying to take pictures of her. However, she does have some respect for him and his wisdom of martial arts and will listen to him on occasions. She's also angry at him for influencing Kenichi to become more perverted and how he's taught him some perverted moves. She is also not above lashing out or even physically assaulting him if she wishes and is typically seen with Shigure when they attack him.
Miu thinks of Apachai as a very gentle man, but also gratefully fears his monstrous strength due to him unable to control it and having put Kenichi in a near death state before but was later gratefully relieved he was finally able to hold back in training with Kenichi. She's sometimes annoyed by his childishness and his enormous apatite due to how he doesn't know any better. She deeply cares for Apachai as a part of her family as she was horrified when she saw him heavily injured from Agaard and was relieved to see him alive and well later.
Miu and Shigure, due to them being the only females at Ryozanpaku, have a sisterly bond and enjoys Shigure's company and tries to help her open up more. Shigure even has offered to help her prepare dinner before. They are typically seen at times in the hot springs talking about things she can't talk to others about, showing that Miu has a strong trust in Shigure. Shigure has even encouraged Miu to respond to Kenichi's feelings knowing Miu also has strong feelings for him just as Kenichi does towards him. However, Miu does seem to fear Shigure's training methods since she doesn't seem to know to hold back much and was relieved to see her and Kenichi alive after her trip, which depressed Shigure. They are also a dangerous duo when they fight together when they typically fend off Kensei's perverted antics.
Miu met Renka when she came from China to bring Kensei back and when she saw her clinging to Kenichi's arm and wanted to bring him back with her, she was upset but greatly relieved when Kenichi didn't want to go with her, which was something Miu wasn't fully able to understand. Miu continuously becomes irritated, angry and even jealous when Renka constantly tries to do things together with Kenichi causing Miu to (unintentionally) treat Kenichi with anger. When Kenichi told Renka how Miu helped change him and though Renka refused to give up, the two officially became rivals over Kenichi's affection. Miu also has a liking to her hair and plays with her in a cat like manner due to her hair and Renka's habit of chasing moving things and the two become good friends regardless.
When Renka transfered to her school just to get closer to Kenichi it caused Miu to become even more jealous and is constantly making sure she doesn't take Kenichi away from her and even will lash out at Renka and tell her to stay away from him, prompting others to state how Kenichi must be lucky to have those two around him. Renka has shown to actually respect Miu and Kenichi's relationship with each other knowing how they feel for each other but won't stop herself to try to win him over. Renka even told Kenichi she knows how strong Miu is and respects her strength and was worried when she was kidnapped and relieved when she was brought home.
Unlike Kenichi's frequent mistreatment towards Niijima, Miu treats him with kindness most the time. However, like every other character in the series, she comments on his alien and manipulative nature like all the others. She constantly is naive thinking he and Kenichi are "best friends" with the two of them call themselves "bad friends". She will also grow very irritated by his bad habit of keeping things from others such as how he made her fight over a disc that held no importance and she was very angry that he did that and she threw little pieces of the disc at his head constantly. Niijima also tried to win her over from Kenichi, but Miu doesn't like him like that and only responds back as a friend.
Kenichi is the first friend Miu had ever made and has a strong bond with. She first accidently tossed him from behind and apologize to him and at the same time recognized him from a long time ago. Miu was even the reason Kenichi decided to move into Ryozanpaku to become stronger. He constantly tries to win her affection by impressing her but she's mostly oblivious of his true feelings for her and just views him as a very good friend, however, she is very kind towards him and often comforts him when he's upset or half-dead from the masters' crazy training methods. Though she's mostly oblivious of his feelings towards him, early on however, she's repeatedly shown to harbor feelings for him and maybe, even deeper feelings than she lets on, such as becoming very flustered when they are called a couple, unable to understand the relief of Kenichi refusing to go to China with Renka and perhaps most famously, becoming rather possessive and even jealous of him whenever another girl shows affection for him. She was also very happy and blushed when she heard Kenichi talk about how much he cares for her.
After Kenichi saves her life on the school ski trip, she becomes much more open and physically receptive with him, going as far as to tearfully hug and thank him for saving her and staying alive. Since then, she now acts more happy around him and talks more about personal things that she normally can't tell others. Every time Kenichi is left severly injured, she's always hugging him admitting how glad she is that he's alright. Miu even shows jealousy whenever he is around other girls and even is upset when she can't spend time with him.
By the time of Miu being left alone with Kenichi for a while when the masters were missing, in addition to starting to realize Kenichi feelings for her, she appears to have started realizing her own feelings for him, going as far as kissing him on the cheek to show her feelings for him. While they didn't get the discuss the matter further (due to her grandfather witnessing the whole thing and scaring the two), several people at school have since noticed Miu being more cheerful and energetic, as well as as more eager to be around Kenichi. When she thought Kenichi was killed by Hongo, she shed tears of sadness and anger and fought angrily to avenge him while unable to control her emotions from believing he died. As stated by Jenazad's observations of her around him even under his control, Miu's feelings for Kenichi have developed even further and has fallen in love with Kenichi. Even under Jenazad's control, Miu was able to hold back due to her feelings for him. Kenichi's devotion towards Miu is so great that he's even willing to die to bring her back to the light and out of Jenazad's control. Miu has even stated she does not mind dying for Kenichi so he can live and has the utmost faith in him by placing his hand on her heart to show how much she believes in him.
After the Tidat incident, Miu is even more happier around Kenichi and much more closer and even intimate around Kenichi as noted by Ukita. Kenichi himself seems to have finally gained more confidence in himself due to this and even convinced her to ride the merry-go-round together since she's always wanted to, which Miu was very grateful towards and even blushed while riding it with him. During her third fight with Rimi, as Miu was losing being unable to control her Dou ki, Kenichi managed to snap her out of it shouting for her not to be afraid of her ki or Junazard's curse, stating he will be by her side. His words reaching her, Miu stood, in control now and smiled down on Kenichi, stating she heard his voice and managed to defeat Rimi with her new control. Rimi stated that Miu was able to control her ki was because of her love for Kenichi.
Takeda and Miu were originally enemies, but once Kenichi defeated him and he left Ragnarok, the two eventually became friends and typically is kind and polite towards him and encourages him when he wants to get stronger. However, Miu is oblivious of Takeda's feelings for her despite him outwardly showing it by constantly calling her "honey". He, like Kenichi, constantly tries to look cool in front of her and wanting to protect her and even tries to be gentlemanly towards her only for her to respond back as a friend. However, he restrains himself to let her choose who she wants to be with due to his great respect towards Kenichi. Also, he told Kenichi that if he lost his sparring match, he would tell his true feelings to Miu and, though he lost and said he only said that to motivate him, the look he gave her afterwards proves otherwise.
Kisara and Miu were originally enemies due to Kisara being in Ragnarok and Miu having easily defeated her. Kisara wanted revenge so she decided to ruin Miu's play, but Kenichi stopped her and decided not to. When Miu saw her seeming treating a cat badly, she wanted to kill her, however, once she saw that she was really treating the cat kindly, she decided to stay with her to find a home for it and, eventually, became good friends due to their love for cats and have since then developed a type of sisterly bond. Miu even is aware of Ukita's feelings for her and even supports her to respond to him knowing she has feelings for him also. Kisara even was very worried when she heard Miu was kidnapped and wished Kenichi good luck in finding her and was later happy to have her home. Kisara also like to tease Miu about her feelings for Kenichi despite her bashfully denying them. Kisara and Miu also talk to each other about relationships with each other and even asked Miu if she had done anything special alone with Kenichi since the masters were gone for the time, which caused Miu to be very flustered.
Miu met Ryuto when they both were six and, thinking he was the one who blew the whistle to help her notice the thugs from behind (though it was really Kenichi) thanked him for helping her, causing Ryuto to develop a crush on her. It was this crush that led him and Kenichi to fight over the yin-yang badge she gave Kenichi and eventually end their friendship.
After meeting ten years later when he was Odin of Ragnarok, Miu was shocked seeing how much he hates Kenichi and demanded to know why the badge was so important and he said it was because he did something unforgivable. She later watched his fight with Kenichi and was worried when he was left defeated and if he may have died from the building but was relieved for Kenichi's sake that he survived.
They would meet agian during the DofD Tournament and Ryuto would keep her from chasing after Sho. She would demand to know about him and Ryuto would at least tell her about his bloodline and convince her to go back. When Miu followed them to the aquarium for a meeting, she ruined it as Rimi was also there and they got into a fight. Ryuto did admit it was nice seeing her again and Miu helped push his wheelchair due to the pipes on the ground (unknowningly making Rimi jealous). She then stopped when Ryuto left and instead asked Rimi to push her, to which she did happily.
Miu first met show when she wanted to go see her mothers grave with Kenichi. When she saw a bird stuck in a tree she tried to help save it and so did Sho and at that moment, Sho took one look at her and immediatly fell in love with her at first sight claiming she had "wings" like him. When he told her he was Yami, she attacked him but once he said he knew her father, she gave in wanting to know more about her father. As she was going away with him on his bike, Kenichi noted sadness in her eyes and she did admit she didn't want to go with him, but she was desperate to know about her father. Once Kenichi convinced her to not leave with him, Sho let her stay, but not before kissing her on the cheek (an act that made Kenichi very angry and even cried blood from his eyes) which made Miu blush and Sho would say to himself about how he believes she belongs on his side. She would wear his earing due to him taking her hairclip and wanting to take it back.
At the DofD Tournament, when they would meet again, Miu would be happy to have regained her hairclip back and would immediatly attack Sho stating as he's YOMI she would defeat him for Kenichi's sake. Sho, realizing he would need to use force, attacks her and knocks her out to kidnap her under the belief she belongs only on their side in the darkness. When Sho almost killed Freya, Thor and Takeda, Miu entered her berserker Dou mode and Sho was actually very happy that she fell into the darkness. He told Kenichi he couldn't bring her back but was shocked that he did and swore they'd settle things in the tournament and told Kenichi that he can’t protect Miu from all those trails before leaving. Once their fight began and Kenichi was almost killed by Sho, Sho told Miu that only he could protect her and said he loves her. Miu, while moved by his love for her, Miu felt something about Shō that she liked (despite what he said), but rejected him after Kenichi already promised her that. Kenichi got back up after Miu shouted for him. She even ran passed Sho and only was worried over Kenichi and was happy Kenichi defeated Sho. However, Sho protected Miu at the last second from a soldier shooting at her and took the bullets for her. As the soldier was defeated and Sho was dying from blood loss, Miu shed tears over his death and watched as he made Kenichi promised to protect Miu since he can't and Kenichi and Miu mourned his death.
Despite being dead, Sho would help Kenichi rise up and remind him to protect Miu from Junazard's control and ultimately helped Kenichi fight to save her from Pengulu.
Seeing that Chikage is similar in terms of not being true to herself, Miu made it her goal to make sure Kenichi wouldn't have to fight her due to his refusal to hurt woman and how she saw that he just wanted to be friends with her. Miu believed only she could get through to her and fight her and when she said she should be true to herself, Chikage told her she's doing the exact same thing as her. This caused Miu to realize that even though she's opened up much more and gained so many friends thanks to Kenichi, she still was not being true to herself and decided the next day at school to no longer braid her hair or wear glasses to prove Chikage wrong, which surprised her. Since then, due to Miu constantly trying to have Chikage open up, she's gradually become more open and started to act more like a child having fun. Chikage even showed compassion towards Kenichi when she was kidnapped by Junazard and wished him good luck in finding her.
Miu and Rimi first met during the hunt for the disc on Yami and, in Rimi's opinion, "love rivals" for Ryuto, which leaves Miu confused as she doesn't have feelings for Ryuto. In there first fight, Miu was impressed at Rimi's speed outmatching hers, but was able to keep up with her and later overwhelm her once she fought seriously. Miu was also mostly focused on getting Rimi's gold shoes due to her need for Ryozanpaku's financial needs (which Thor notes she's just stealing them). Once Thor broke the disc they tried to get, Rimi left, but promised they'd settle things.
In there meeting at the aquarium, Rimi asked Miu what Ryuto is to her and the two began a second battle, but, due to Miu's training under Junazard, Miu overwhelmed her completely and likely would have left serious injuries had Miu not been so focused on the gold shoes. Once Kenichi and Ryuto found them, they had to stop and Rimi left with her, but would cause Rimi to train under Ogata to defeat her and gain Ryuto's affection. In there third confrontation, Rimi would overwhelm Miu due to her new Dou ki and leave Miu unable to keep up this time. Miu would be left shocked and angry at Rimi for leting herself gain such dangerous power despite knowing what it does to her loved ones and finally decided to go all out to defeat her. However, once Rimi also went all out, Miu was overwhelmed to the point of being unable to defend herself from Rimi's brutal assalts. But once Kenichi helped her by telling her not to be afraid of her ki, stating he'd by by her side, Miu was able to regain herself and overwhelm Rimi. However, due to Rimi's obsession with defeating her caused her to unleash the dangerous Seidou Goui technique via Ogata's permission. As Miu was overwhelmed, she wondered how to defeat her without killing her, showing she still didn't want to harm Rimi. The fight ended in a draw due to Ryuto's interference. However, Rimi died from the negative affects of the Seidou Goui technique harming her body due to her current injuries and emotions running wild. Miu morned her death and blaimed herself over it and even attempted to attack Ogata for causing her death.
Due to Junazard interfering with Sakaki's and Hongo's fight would cause Hongo to accidently knee-jerk Kenichi and almost kill him which caused Miu to become enraged and lose control of her emotions and angrily attack Junazard in blind rage only for her to be easily defeated. He would kidnap her and bring her to his country and brainwash her into a heartless killing machine full of rage who he renamed "Bulu". As Bulu, Miu was very loyal to him and did anything he asked without question, even killing people. However, she wasn't able to kill Kenichi due to her feelings for him and her still maintaining her sanity deep down. Junazard would later try to have her killed when she didn't live up to his expectations. However, Kenichi would be able to bring her out of the darkness and back to her old self. Once Junazard was killed, the elder managed to free Miu of her brainwashing completely and now no longer has to worry about Junazard ever hurting her again.
Being the cause of Ryuto's paralization and the usage of his disciples as guinea pigs, Miu has since viewed Ogata as an evil and dangerous man. She is well aware of the danger he possesses, warning Kenichi not to get near him and how crafty he is. After Rimi's death and how Ogata showed no remorse over her death and planned to use another disciple after her, and enraged Miu attempted to attack him only to be repelled with ease and left with fatal injuries as a result. This would cause Kenichi to attack Ogata in anger and fight him despite Miu's pleas not to.