I think he did. that's the only thing that makes sense based on what we've seen so far
I don’t think it was Aoki. If it’s Aoki, he would do something like taking responsibility. I guess he just feels sorry for him that he couldn’t protect him or find the real culprit behind. That’s why that man said “it’s okay, it’s not your fault” kinda forgiveness.
He didn't, there's already a bite mark on Izumi when he approaches him, and also wanted to find the culprit.
It wasn’t aoki, there was a link uploaded in the comments of the next 2 chapters and it was some one else that violated him. Aoki js felt responsible for what happened.
So... did Aoki bite Izumi?? if not, why did he say "I've always forgiven you?" if he was not bitten by him why would he forgive him?