Itokoi Chidori

Akio Kosato is well-known by the girls in his school for his skill in creating "love potions," though he himself receives no romantic attention. That changes when a mysterious girl named Chidori appears and gives him far more attention than he ever wanted. It turns out that Chidori is Akio's long-forgotten cousin, and there may be much more to Akio's family than he realizes.One of the first series to have a volume deemed "harmful" under Tokyo's Bill 156.