Hello! I’ve been looking for an old manga about a son of a demon being sent to Earth along with his rival older brother. Their mission is to prove themselves to be worthy of becoming the next successor of their demon father king. The MC’s older brother became a leader of a mafia/gang while MC has only become a happy-go-lucky kind of guy. He even slept with a family consisting of a sex-crazed monkey looking grandma, mother and daughter who both have masculine features. *The art style of the MC is kind of a stocky build.