Who's ren? When did appeared?

Our blonde dude paid ten to date the twins and they almost killed him but he had a sick grandma to take care of. So they are helping him out by killing his rich family that is ignoring his situation so he can get a large inheritance to live with his grandma and be set for life. And the kid said it was cool so the plan is in motion

But what chapter was he introduced?

Nm, i found it. CH 144