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Three cousins—Haruhiro, Fuyumi, and Natsukichi—from a wealthy family turn seventeen and are sent by their grandfather to participate in a family coming-of-age ritual. Their parents encourage them to do well, as the cousin who performs best will receive a reward. They are taken to an aquarium, though the reason is unclear. All three experience an unsettling sense of familiar déjà vu. The story was first published in Deluxe Bessatsu Shoujo Comic on May 2, 1998.