Jadeite watches Sailor Moon using her Moon Tiara Action attack, seeming angry that he cannot defeat her. A monster named Tetis comes up behind him and says he can't believe he is having such a hard time defeating a little girl. Jadeite asks what she is doing there since she is supposed to be working directly under Queen Beryl. Tetis says that she is there because she adores Jadeite, but he always gives her the cold shoulder. Jadeite commands her to leave, but she claims that she has a new plan for collecting energy called Project Romantic Cruise.
Usagi watches a commercial on TV for the "Romantic Cruise." At school, Usagi and Naru talk about the cruise, and Umino daydreams on going on the cruise with Usagi. When Umino realizes that Usagi and Naru want to go, he says he should have saved his invitational tickets for them (he gave them to the lady next door.) He does inform them that there is a raffle going on down the street where they are giving away a free pair of tickets for the cruise. Usagi immediately dashes out of the classroom and goes to the raffle. She tries to win ten times, but to no avail. As she is leaving she runs into Rei, who is on the way to her own school. Rei says that she is not interested in cruise tickets because they don't have time to waste on that sort of thing. Even so, she buys a turn at the raffle. She uses her psychic powers to cheat and get the winning ball. Usagi calls her a hypocrite as Rei jumps up and down in celebration. At the park, Usagi begs Rei to give her the tickets or at least go with her on the cruise. Ami comes up and sees them arguing, and Rei invites Ami to go talk with her. Rei asks Ami to go on the cruise with her since she doesn't want to go with Usagi. Rei intends to find a boyfriend while on the cruise. Usagi is listening in and vows not to give up on going herself.
At the dock for the cruise ship, Usagi reveals to Luna that she intends to use the Disguise Pen to transform and sneak onto the ship. Despite Luna's protests, she transforms into a "beautiful camera woman" and boards the ship. Jadeite, dressed as the ship's captain, watches as the crowd of people come aboard. He tells Tetis that he is impressed with how she used her "evil seawater powers" to change a wrecked ship into a luxury cruise. The true nature of the ship is shown and it appears to be a rusty wreck, although the people onboard only see the illusion. Tetis says that with her evil powers something like this is easy to do.
The ship's passengers seem to be having a nice romantic time, although Ami and Rei realize that they are the only people who came on the cruise not as a couple. Usagi plays with her new camera while Luna says that she thinks something is wrong with the ship. The captain appears and scares Usagi, so she stuffs Luna back in the camera box and pretends she is lost. Jadeite thinks to himself that Usagi bothers him for some reason, but he doesn't know why. He leads Usagi through the ship's halls, but Tetis interrupts and tells him that it's "almost time." The two of them talk about collecting the human energy all at once while Usagi and Luna spy on them and decide to follow them. Jadeite and Tetis gather everyone in the reception hall and tell them they will put on the most romantic show ever seen. Tetis transforms into her true self and Ami and Rei notice that she is actually a monster. Tetis appears to be collecting energy using the disco ball on the ceiling. Everyone on the ship passes out except Ami and Rei, since Tetis was only collecting "love energy" and they did not come on the cruise with boys. Jadeite criticizes Tetis' miscalculation, but Tetis sends monsters after Ami and Rei. Tetis and Jadeite intend to make off with the stolen energy, but Sailor Moon appears at the last second and stops them. Tetis knocks Sailor Moon out the window and the two of them land on the ship's deck with Luna. Luna realizes that Tetis can control seawater and tells Sailor Moon to be careful. Inside, Sailor Mars and Mercury have transformed and defeated the small monsters. They hurry outside and Sailor Mercury uses her Bubble Spray to surround Tetis in a fog. Sailor Mars hits Tetis with her Fire Soul attack, leaving an opening for Sailor Moon's Moon Tiara Action. Tetis is defeated, but Jadeite confronts the Sailor Warriors and tries to raise his own magic against them. Before he can attack, he is suddenly teleported away. He appears before Queen Beryl, who is angry that he used Tetis without her permission and allowed her to die. Queen Beryl promises to pass judgement on him at the palace later on once she hears his excuses.
Everyone on the ship goes back to normal, but they see that the ship is really a rusting pile of junk and send out a distress signal. Usagi and Rei vow to go on their next cruise with a boyfriend instead.