You guys have to take some parenting courses before having a child please if you don’t want to having a diffucult relationship with your kids..
It's not about that at all. His biological mother died and ontop of that his father is a yakuza. I would assume his bio mother was also a house wife but if you think about it, everytime toma cries it's a relief knowing he's still a kid and haven't matured that fast because his bio mother died. Before his "mama" came he rarely smiled and was as dense as Daiki but now he gets to enjoy the feeling of being a kid. And even though he's only a kid, it's clear that he's developing abandonment issues.
Just wear the ring as a necklace. You can hide it anytime. Problem solved!