Kang Hyunseh (Kim Jae Won) grew up without knowing his father, who is the CEO of a large construction company. Due to the lack of fatherly love, he was recruited by a gang and became a third rate mobster. After his mother's death, he inherits a kindergarden, but he must go through a hundred days of training in order to get it, so he becomes an assistant teacher under a kindergarden teacher Yu Mirae (Han Ji Min) and they develop romantic feelings for one another. However, the property it sits on is in the middle of an amusement park production, called "Rainbow Park", which is in charge by Hyunseh's father who Hyunseh dispises extremely. Hyunseh's boss needs the money from the construction company so he is manipulating Hyunseh's hatred towards his father and threatens Hyunseh's father with the kindergarden Hyunseh has. Little does Hyunseh know that Choi Shiwan (one of the managers who work for Hyunseh's father), who is the ex-boyfriend of Yu Mirae, struck a dirty deal with Hyunseh's boss and is trying to outscore everyone.

Produced by the same production team as My Girl and Delightful Girl Choon Hyang.


Cast
* Han Ji Min as Mirae Yu
* Kim Jae Won as Hyunseh Kang
* Kim Ji Hoon as Shiwan Choi
* Lee Mi Sook as Ara Go
* Jung Tae Woo as Nalchi/Su Bong
* Son Byung Ho as Dongpa So
* Byun Hee Bong as Ildo Jung
* Jang Hyun Sung as Manho Jang