I think it's good there's finally a manga I read where they actually addressed the fact that regression is a thing that happens. People keep expecting these adults in children's bodies to be still adults, mentally, while that's just not realistic. Your mind is scarily adaptive and WILL adapt to the fact that you're no longer an adult if you keep being treated like a child. That's why Ryouma is only now really starting to regress, because he got a family and friends that treat him like an 11-year-old.