Schoolgirl Miho after losing mother several years ago, with Father the living of two people were continued. Father was a captain of a large-scale cruise ship, but descended from the ship atfer mother's death. However, Miho noticed that father wanted to return to the ship.

Miho who came to be able to do housework etc for myself in general, the return was recommended by a colleague at that time and the back of father who was hesitating was pressed. In that way the official return to a captain is finally decided on father who would return to a ship after having worked as a vice-captain for a while.

Then, a story is proposed from best friend Moribe Jun to Miho. Because a short-term part-time job is recruited by the commemoration cruise, the invitation of doing the work together. Miho who gets on the invitation during summer vacation.

It is summer vacation the training of several days is finished and voyage starts finally. Though it has a hard time in the part-time job that doesn't become accustomed, Kurusu Nonoka the idol who is doing a event on this cruise, student violin player Otoha Saki, it becomes intimate with dealer Mizunashi Nadia in the casino etc, the time happily enhanced is spent.

This summer vacation will be memories of a lifetime... Miho was sure of that, but never thought that a nightmare was waiting.