Well, first, he records the Confession Festival and uploads it to whatever the story calls YouTube(I think it's called YouTube, but can't remember off the top of my head) thus exposing Maru and embarrassing everyone involved. Second, he starts colluding with another character's scheme to keep Maru away from the entertainment industry no matter what underhanded methods they have to use. That's kinda it for right now, but basically taking away Maru's right to decide his own future is pretty selfish and scummy in my book. It's still pretty early in the scheme plot, so I'd expect Tetsuhiko to add a few more offenses on here.