On his 20th birthday, Joosuh Yoo declares he wants his long-time neighbor Hyunwoo Kang's body. Hyunwoo expresses that Joosuh's too young for him, but the passionate and headstrong Joosuh persists and Hyunwoo gives in for one night. After their night together, Hyunwoo continues to treat Joosuh like a child. “You're all I need.” Hyunwoo has known the kid next door for a long time, but contemplates over how to take Joosuh's obstinate character to cling onto one single person. Will Joosuh be able to win over Hyunwoo's heart?