Yuuki has a visual impairment, and that made him a target of your bullying. Your other classmates contributed in the bullying, but you were the main and most relentless perpetrator. You made his one year in eighth grade a living hell. You didn't hear a word of him since. Back to the present day, you were riding a train to Yokohama Station when you bumped into Yuuki. He didn't know that it was you, his middle school bully who he bumped into.