Yunho (20yo) and Jaejoong (15yo) are cousin but their relationship is not like what we expected like other cousins should be.  Jaejoong is kind of childish, spoiled-son, diva type, and clumsy while Yunho is the very strict boy, who only love to study, independent boy and he hates someone like Jaejoong. he hate Jaejoong for being too clingy, clumsy and even soo childish for his age which make Yunho think Jaejoong had suffered a mental problem at first but no, Jaejoong is indeed a healthy teenager like him, but..*sigh*. vice versa, Jaejoong hate Yunho because Yunho always refuse to play with him, arrogant, never listen to what he want and always flick his forehead.but still, the clumsy boy still love to come over to his auntie's house necause he can get into fight with Yunho, and even quarreling with the taller man. but little did he know, he actually fall in love with the taller man and he's too clumsy to even realise his own feeling.  one day, Jaejoong received a news that his parents need to stay at Japan for 4months and all he needs to do is to stay at his auntie's home within  4months and the decision actually displeased certain Jung in the house. this is because Yunho need to be a babysitter for 15yo clingy Jung Jaejoong, his cousin..