Ichiban Boshi[]
Koume Moroboshi[]
Koume is Yuudai's little sister. Yuudai cares for her deeply, although sometimes teases her. Three years ago, Yuudai was greatly injured during an accident, which left him crippled. Koume blamed herself for what happened, ceasing from speaking. Yuudai though didn't want Koume to blame herself, leading to him undergoing rehabilitation and become far stronger than before. Despite remaining silent for a while, Koume finally spoke during Yuudai's match against Ikki.
Mother[]
Yuudai and his mother often treat each other aggressively, but actually, care for each other quite a lot.
Bukyoku Academy[]
Byakuya Jougasaki[]
Byakuya is a friend of Yuudai. They faced each other in the finals of the 61st Seven Stars Sword Art Festival, with Yuudai winning. They have shown having a good relationship, though Yuudai doesn't completely agree on Byakuya's views on fighting.
Rentei Academy[]
Kiriko Yakushi[]
Kiriko helped Yuudai during his rehabilitation, and they still have a friendly relationship, with Kiriko performing regular examinations on Yuudai. Despite knowing each other for a long time, their relationship isn't romantic, as Kiriko has mentioned that Yuudai isn't her type.
Hagun Academy[]
Ikki Kurogane[]
Yuudai and Ikki respect each other and recognize each other's skills. They have a rather friendly relationship, with Yuudai offering a free meal to Ikki and his friends before their match.
Tohka Todo[]
Yuudai and Tohka faced each other in the semi-finals of the 61st Seven Stars Sword Art Festival, were Yuudai managed to defeat Tohka. They are shown having a rather close relationship and have been shown discussing their future plans with each other.