Talk:Shuu Tsukiyama/@comment-202.62.16.128-20150818154440/@comment-10733658-20150818155542

It was explained in the first novel, in the story about him and Chie.

He takes her to visit a hospital his family has stock in, and explains that he's utterly fascinated with how humans manage to flourish in spite of being ill-suited to survival. Especially, he's fascinated with how they care for and support their weakest members -- he wants to be close to this and understand it better.