Golden Time Episode 17: Why so suspicious, Mitsuo?

So Banri has returned to his hometown for a very conveniently-timed high school reunion right as he’s choosing to face his past. As for Mitsuo, he’s strangely suspicious after finding out about Banri’s accident. He also reacted pretty strongly to finding out Linda and Banri knew each other. Protecting Kouko? Seems unlikely. Worried he might lose Linda to Banri? Possible, I guess, but where’s the trust? Aren’t those two supposed to be good friends? Worried about Banri in general? Also possible, but doesn’t make for good drama. Any other theories?

Anyway, next week is the reunion. Banri will learn more about his past. What exactly has been happening with Ghost Banri in the past couple of episodes? Is he silent because he feels guilty about what he did? I would expect that the reunion would get his attention. New Banri has to deal with him eventually.