 An imprudent early return to the court severely compounded the injure in that knee, leading to a basketball hiatus of over a year.Although he eventually healed, Mitsui was embittered by his exclusion from the court and quits basketball to become the leader of a delinquent gang.His gang fights with Ryota Miyagi during the latter's first year, and during one such fight, Miyagi beats Mitsui senseless before taking a beating himself, knocking out a few of Mitsui's frontal teeth and leaving the both of them hospitalized until after the practice match against Ryonan.