Banri was knocked over the bridge by Linda
In episode 5, a Flash Back
shows him interacting with a girl in the woods when he says he kept seeing a flash of light outside his window in the hospital. Other ones show him getting knocked over by someone in a scooter, and in the flashback in episode 5, a scooter can be seen near where Linda was watching the hospital. She hasn't said anything to him about being in his past because she feels really guilty about him losing his memories in the first place, and doesn't want him to know about it, even if it was a total accident.
- According to the person in question, she was on her way to meet Banri when he had his accident, so she probably didn't directly cause it. However, Linda's refusal to make a quick decision about their relationship put Banri in extreme turmoil, and this may have been related to the accident.
- I always thought it was the guy Linda's brother's fiance was having an affair with.