Golf is an ill-behaved high schooler living with his father. One day, upon his father's return from a trip, he meets Bank, his new step-brother from his father's new marriage. Golf is taken by surprise with this new revelation. Bank is younger than him by four months, but this doesn't ease Golf's discontent at all. He does not want a new family, including a younger brother. After initially treating Bank badly, Golf and him can't help but get close. Will the feelings of love between siblings grow beyond that?