This is fiction. Anything goes. Even if it's supposed to have realistic themes, it's still fiction. Would I support a romantic relationship between a 15 year old and a 33 year old in real life? HELL NO. At the very most I would call the cops, and at the very least I'd wash my hands, sever all ties with the people involved, and feign ignorance down the road. But, since this is fiction, and since I like love stories with forbidden themes like age-gaps, incest, etc. (except same-sex romance), I'm seriously hoping for a romantic development between Mashuu and Satoko. Will it happen? I'm leaning towards no because of what the author said, but I'm still hopeful, and if not, well at least Mashuu finds a maternal figure in Satoko.