There's a story that must be told - hidden beneath the beautiful blue waves of this ocean city. Kyoya, a teacher at the Underocean school, lost his memory in an unfortunate accident that took place 3 years earlier and since then has been taken of by a beautiful young girl named Miyu.

It's natural that Miyu would become the center of all his wildest fantasies, but Yumi has a suspicious feeling that there may be more to Kyoya than he lets on.