Shō was bought as a young child from the Kuremisago by Yami and was trained harshly and extensively for almost his entire life. He quickly became Akira Hongō's disciple, defeating many opponents, but was believed to have a weak heart that lacked mercilessness and therefore was not allowed to inherit anything. At one point Yami even considered killing him, but he was defended by his master and had his life spared when he was told to kill a baby bird he had found in front of the members of Yami, which he did without a moment's hesitation, though he secretly crushed some grapes he picked. It is implied from Seta's and Hayami's karate styles that Shō was primarily taught a karate centered on the use of knife hands, and from their anger at his death that they shared a type of comraderie or friendship during their tutelage under their master.
At some point, he was sent to Silcardo Jenazad to be trained in Pencak Silat. However, before he was trained Silcardo had him fight against Radin Tidat Jihan to see if he was worthy to learn Silat. He prevented one of Jihan's moves and Jenazad liked him and was willing to teach him, just like the One Shadow asked. Later with Hongō, Shō said that Silat is as awesome next to Karate due to the fact that it can adapt to anything, is freely changable, has so many moves, and is complicated and bizarre.
Later, he was chosen as the leader of Yomi and was taught by the other members of the One Shadow Nine Fists to inherit their martial arts, during which he created his Kyu Geki Issatsu (Nine Strikes One Kill).
At some point, he would meet Natsu Tanimoto and would eventually become good friends. The time he met him would be when Natsu was still the sixth fist of Ragnarok. Shō would reveal some personal things about his life and the two were close towards one another. Shō would later be shocked by Natsu's defeat at the hands of Kenichi and decide to fight him someday.