Its possible that in this universere, only fated pair can do the bonding mark. Or maybe no marking at all(the marking thing is actually quite stupid tbh)
It is still on going. There's already 2 chapters for 2nd volume. In the next volume, Yuujin already marked him and Rei did the same (bite each other's nape). As what Yuujin called it, "It's a proof of our love" uncle will go down with his shits.. I hope they will upload them here.
After 7 years and they still haven't paired
ヽ((◎д◎))ゝ