Sinopse: Won Yo-il, bullied every Monday because of his unusual name, endures his fears and returns to high school, where he meets his prickly classmate, Gu Yoon-won. Yoon-won, who repeatedly teases Yo-il but then approaches him, one day hands him a letter of intent, offering to become his second younger sibling. But something about this younger sibling is suspicious…?!

Origem: Coreia do Sul.