they're gonna do it when they get together forreal to seal the deal + hyuno will get tired of having one nipple swollen so dojin will have him pierce the other one "so I can suck the other and it won't be as swollen" and he end up with equally swollen nips lol
i’m starting a petition called “Pierce the other fucking nipple dude !!” (╬ ̄皿 ̄)