Tachibana Makoto is a doctor who is very experienced. He lives alone, or at least did, before he took the young, Nanase Haruka into his care after a his parents died in an accident. Haruka was only ten years old. Knowing that he would have a new parent, Haruka tries to be as well behaved as he can, despite the autoimmune disease he has, vasculitis. As well as the task of growing up with one parent, and it wasn't even his own.