Kazuki Tsukigase is a high school boy with a secret, and he transfers to a school on a remote island to get away from anyone who knows him. Rumor has it that people disappear at an inlet on the island. One early summer day, while exploring there, Kazuki finds a girl lying unconscious and takes her to the clinic. When she wakes, she can say little about who she is beyond her first name and that she is 16. She also murmurs the year 1974, and what that word means becomes the question at the heart of this mystery romance film about a boy meeting a girl.