Yuuka is Shuuya's younger sister. She ends up in a coma after being hit by a car—a tragedy that happens right before one of Shuuya's biggest matches. The guilt hits him hard. He becomes convinced that if he'd never gotten so serious about soccer, Yuuka wouldn't have been in that place at that time, and he quits the sport entirely.
It takes Natsumi Raimon stepping in to help him through it. She talks him down from the spiral, and eventually Shuuya finds the strength to get back on the field.
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