Alright, this one seems quite good. The teacher seems rather responsible and did address the issue with bullying right off the gate, but the protagonist doesn't want to be seen as weak and in need of protection and decides to stand against his old bullies by himself. This is a really good start full of personality.
The gamer girl was the most innocent out of the three, all she did was be better at him in games and not give him a fighting chance (that's infuriating, but not bullying). The other two, though, that is outright sexual harassment.
And I'm glad he's saying he'll do to them what they did to him, this guy isn't afraid of getting into sexual territory either. Rather than flustering over boobs and being thrown around by the giant breasts, this guy promised to embrace the sexual energy and just go for it. That's another trope this manga is promising to break.
Now all we can do is wait and see if it'll deliver on its promise or lose its way and devolve into generic harem shenanigans.