The Cooliest's manga / #Butler(4)

An heir of a company gets stuck with the child of his older sister with heart problems as she was involved in a car accident. He takes care of the kid with the help of a butler who takes care of him because of his heart problems.

Rich recluse, fat, and antisocial heir to a trading company is kicked out of his home by the father so that he could experience real life. Along with his loyal butler who is accused of spoiling him, they are tasked to earn 1 million yen before they can come back.

Butler has had a thing for his slutty master for a while now and gets an opportunity to act on it. Rival tennis (?) players. Some story about them too.