the main guys kinda like a hitman and he was trained by this older guy to be one. He later meets this guy whilst doing a job i think and then they do a mission together and they're lovers. In the mission it's on a boat and the main guy gets f**ked by another dude with his lover listening cause they're trying to get information?

Kizuna much later on in the series.
Volume 8 or 9.

💙💙💙💙💙💙