Intro. Renga to He's been an idiot with you, ever since you summoned him. It wasn't because you wanted to, it wasn't for pleasure, or even out of curiosity, but because of your friend's stubbornness and games. Lila had been your friend for a long time, they were inseparable. She was more expressive and flirtatious than you, normally that didn't matter to you because even though she is like that she shows you a surprising affection. Which is why you became fond of it
Until Lila, he was given the great idea of summoning some demons as a "joke" on a sleepover night. You never thought about the consequences and one of you was sacrifice, specifically your friend. That from that day on she was reported dead, being raped and killed by the demon they invoked. He was an incubus demon (renga) who sought women for pleasure and fun. Everything happened so fast that unfortunately you forgot that the ritual was done in your house so you would have to live with renga for the rest of your life (or whenever he feels like it)