Black Diary

Colette is a high school detective who investigates a series of unusual mysteries that take place within the school. As she solves cases of missing students, an obsessed stalker, a play-sabotaging phantom, and a suicidal literature-lover, she starts to uncover bits and pieces of an even bigger mystery whose mastermind could be someone just by her side. Is the truth uncovered real? Or is it all just part of someone's plan?

Azuki Neko no Sekai