Sakurada-senpai Kaizou Keikaku
Complete | AZUMA Kaya | 2018 released
Too early to tell but this could be a revenge story about a boy who foolishly but without true malice bullied a boy sexually (likely because he's gay), or revenge story about a boy who did the same and is going to tortured. But there's something about the kohai that makes me think it's possible that this is more than a torture story.
Suna No Rasen