在这部最美的水剧情片中,11岁的小学6年级学生夏美，和父母住在一起，还有她因为怪病而沉睡了11年的姐姐爱，一家人相亲相爱的一起生活着。这一年她暑假的时候参加了补习班，但是有一天传来了夏美的姑姑在南美旅行的时候出现了航行事故的消息，父母2人急忙留下夏美和爱启程去寻找出事的姑姑。就在那天夜里，爱突然醒了过来……
The story is a variation on the Tom Hanks classic "Big," but instead of a boy finding himself in a man's body, a sick girl falls asleep one day and does not wake up again for 11 years. In the meantime, her baby sister, Natsumi (Rio Kanno), grows up to become a very studious and serious 12-year-old, studying hard at her summer juku (cram school). When her aunt, a free-spirited photographer (Karie Kahimi), goes missing in South America, her mildly scatter-brained mother (Kaho Minami) and father (Tetsuji Tanaka) go looking for her, leaving the girl, Natsumi, to look after her sleeping sibling, Ai (Rosa Kato). Yes, this is a clear case of child neglect, but Natsumi is such a no-nonsense, responsible type that it seems almost understandable. Soon after Mom and Dad leave, she notices that Ai, incredibly, is up and about, with the body of a woman, but the mind of an 8-year-old.
