Ayumu doesn't bother to try in school, he is to depth in thought about his brother. Ayumu ends up meeting Hiyono a blond, energetic, journalist for the school. Soon a murder happens in his school, and through Ayumu's Genius and Hiyono's hacking skills they figure the case.
Ayumu soon learns that the murder and soon to be murders are caused one way or another because of the Blade Children. As the story goes he gets tested by the blade children, the reasoning is because his brother told them that Ayumu could be there savior of the curse. The Blade Children are different through the fact they have one less rib, and have cat like eyes. They never fully explain why everyone is trying to kill them except for that there cursed. "SPOILER" The iris Ayumu's brothers favorite flower is mentioned a lot through the series.
This anime is great for its drama, detective work, some comedy, and maybe romance. Its definitely a must watch. Its not on air anymore so you either have to buy the box-set like me, or find a anime streaming site.