Na Rae opens Na Rae School for the summer, and she invites the members of Rainbow Club to her grandmother's in Muan, Southern Jeolla Province. What the members thought was going to be a funfilled summer vacation turns out to be more of a harsh training camp. But then, an unexpected guest visits them. Additional Cast - Jun Hyun Moo + Henry Lau + Lee Si Eon + Han Hye Jin + Yoon Hyun Min + Park Na Rae + Kian84 + Sung Hoon