Ichiban kirei na mizu (2006)

Inspired by "Big," this story follows a young girl who falls asleep and doesn't wake for eleven years. During that time, her younger sister Natsumi (Rio Kanno) matures into a focused 12-year-old, diligently attending summer school. When their aunt, a photographer, disappears in South America, Natsumi's mother (Kaho Minami) and father (Tetsuji Tanaka) leave to find her, leaving Natsumi to care for her sleeping sister Ai (Rosa Kato). Surprisingly, after they depart, Ai awakens with the body of an adult woman but retains the mind of an eight-year-old.