From what I recall, his parents backstory is that he had a mum & dad. Dad ran off with another man. Mum took this out on her oldest son, and killed herself. Dad then apparently was murdered by the man he ran off with? due to money issues. This is why both son's never experienced things like trips to the fairground, as shizuma's spoke about in this book. It might also explain why they are so protective of each other. Shizuma works as a photographer in a nightclub, which his younger brother used to work part time in. There is more explanation in the other book which focuses on the brother.
Can someone explain shizumas backstory? I kinda got lost with that one
Edit:thanks for explaining, I also meant the blonde mc with the medium length hair :D