Kouko is the daughter of a hospital owner. Did Banri actually meet Kouko after the incident by accident? It seems like he was somehow connecting the flashback to Kouko. Though it's quite a mystery why he apparently escaped the hospital to run in the forest. Was he going to meet someone, got hit by a motorcycle and hospitalised, but wanted to keep his promise and tried to run back to the meeting place straight from a hospital bed? That would certainly seem like something a man of his kind of limited mental capacity would do.

Maybe the Festival club member is the one who biked over him, haha. Or was supposed to meet him, although if the latter, it would be strange Banri didn't already know her.