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.

It’s about a goodhearted boy named Takashi who murdered his teacher at age of 13, to protect his childhood friend Yui. The story revolves around tragedies happening to both of them because of that incident.

From 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.