Aizawa was bullied by Suzuki to the point of becoming truant. He picks himself back up and becomes a teacher. 20 years later, his bully's daughter is one of his students and she's being harassed in class, a secret she keeps from her father.

From DrCoke at MangaHelpers: Kuroba Yo is a sadistic detective who enjoys nothing more than destroying his targets emotionally and psychologically through his deductive reasoning. Toiro Arata is a naive and slightly masochistic boy who gets duped by Yo into becoming his assistant, or slave. These two team up to become the "Black & White" detective, solving crimes and chasing after criminals...