Hachirobe Kosaka was Shigure Kosaka 's adoptive father and her master of weaponry.
Hachirobe has only been shown as an elderly man, with two scars on his balding head and a thick mustache and beard. He has an eyepatch over his right eye and wears traditional robes, and has been shown to carry a fan.
Hachirobe is an easygoing old man, able to recognize talent when he sees it, shown when he expresses satisfaction at taking Shigure in as the Kosaka style's successor. Prior to this, as he had no legitimate successor, he envisioned Akisame as his successor for the Kosaka style, though understood that Akisame had dedicated himself to Jujitsu. He would ambush Akisame in his home as a means to train him, a training that even Akisame said was extreme.
Hachirobe also possesses a curiosity for antiques, such as the Hitogiri Bouchou he received that he asked Akisame to analyze. At this time, he demonstrates a sharp wit even for his old age, able to deduce that it came from Shigure's Father.
Hachirobe has train alot of disciples over the years having almost all of them have be killed over the year. Then meeting and train Rin Tachibana as a disciple. He has created two of the Strongest Techinques of weapons Kousaka Style Shioto Kourenzan and Soutou Kyourenzen that he has pass on to Shigure.
Hachirobe had known Akisame Koetsuji for a long time, and taught him the anti-weapons skills. Sometime later, he calls Akisame to his home and ambushes him to test his technique, calling him to his home to show him the Hitogiri Bouchou that had reached his antique store and pointing him to the mountains where Shigure's father lived.
Later, he takes in Shigure after Akisame brings her in and trains her in weaponry, dying peacefully knowing that he had a successor to carry on the Kosaka style.
Hachirobe is a Grand Master of Weapons from Kosaka Style complete Mastering the art of weapon to the highest peck for weapons and created some of the most powerful technique.
- Weapons Master: Hachirobe was a Grand Master of Weapons. His Skills was never seen.
- Master Teacher: Hachirobe was able to train both Shigure and Rin to the level of Grand Master of Weapons.