This episode begins with Usagi, Rei and Ami talking at a quiet park that overlooks the water. Usagi says that it would be the perfect place for a date and Rei is surprised that Ami knows about a place like that. Ami says she comes there to read when she doesn't have cram school. They come across an older man whom Ami apparently knows. His name is Mr. Kunitachi and he takes care of the park by himself and tends to the plants. He tells the girls that the land owner sold the park and that it will be closing soon to build a shopping district. He is dismayed by this but can do nothing about it. Rei vows to get a boyfriend and bring him there before the park is gone.
Luna is walking across the street and almost gets hit by a truck. Mamoru happens to be there and saves her. Usagi and the girls walk up and see him holding Luna, and Usagi freaks out and yells at him. Mamoru lectures her and says that if she's Usagi's cat she should keep a better eye on her. Usagi grabs Luna from him and swings her around haphazardly as she yells back at him. Ami and Rei take Mamoru's side and say she should thank him for saving Luna. Since they happen to be outside the arcade, Motoki walks out and says hello to Mamoru. The two of them apparently attend the same college. Usagi is surprised both by the fact that they know each other and the fact that Mamoru is in college.
At his hideout, Nephrite plots his next trap as he looks to the stars for guidance. He calls on the beta star of Cygnus, Albireo, which he says is noticeably brighter after 120 years. He chooses the old man that takes care of the park as his next victim to steal energy from.
At the arcade, Usagi plays the Sailor V game while Rei asks Motoki questions about Mamoru. She appears to have a romantic interest in him now. Motoki tell her that Mamoru lives by himself in an expensive high-rise apartment since he is the son of a rich family. He also goes to a very competitive school. Rei decides that she would be the perfect match for Mamoru and vows to go on a date with him at that park. At the park, the old man watches the bulldozers and says to himself that he wishes he could do something to protect the park. Nephrite approaches him, tells him he can save the park, and sends a monster to possess his hat. The hat now contains the power to control animals. The old man sends butterflies to attack the construction workers and the construction stops.
Rei waits near the Juban Bakery, knowing that Mamoru must pass by there on his way home. She intentionally bumps into him and apologizes politely. Mamoru also apologizes and offers to take her out for tea. He takes her into his arms romantically. Of course, this turns out to be a daydream of hers. Still, Rei is really waiting at the Juban Bakery for him and waits for him to come by. The actual event does not go as well as her dream, though - she runs out from behind the corner and falls flat on her face. Mamoru accidentally steps on her head and apologizes and asks if she is okay. When she says she is, he just says that's good and continues walking. Rei chases after him and awkwardly says that she should take him out for tea to apologize, but doesn't know what to say when he asks what the apology is for. She says it's for making him step on her head and he agrees that he wouldn't mind having tea with her. She latches onto his arm, seemingly ignoring the fact that he appears disinterested. They away while Usagi watches everything happen. Usagi yells to Luna that he is a college student and shouldn't be walking with Rei like that. Luna says that she doesn't think he is really such a bad person, but Usagi says it's "impure fraternization" according to the student manual. She decides that Rei is in danger and follows them. Luna points out the obvious fact that Usagi is really just jealous. At the tea shop, Rei tries hard to make conversation with Mamoru, but it doesn't seem to be working. Hiding behind a plant, Usagi tells Luna she will use her Disguise Pen to get closer and hear their conversation. Luna warns her that it is only to be used for justice. Umino comes up to Usagi and asks what she is doing, and Usagi asks if he has any money on him and if he would like to take her on a date. Of course Umino gets excited and agrees, but Usagi is only interested in hearing Rei's conversation. Rei asks Mamoru if he will go somewhere with her and he agrees.
Meanwhile, Ami comes across Luna and tells her that the man at the park is acting strangely. He told her that people like them don't deserve to enjoy nature. They go to the park and a man in charge of the construction project walks through, saying there is no way animals are stopping the progress on destroying the park. He leaves a cigarette butt on the ground and a chipmunk runs up to it with its eyes glowing red. Several chipmunks attack the man at once and he runs away. Luna says that the park is filled with an evil aura and that it must be the work of the Dark Kingdom. Ami worries about Mr. Kunitachi. At that time, Rei and Mamoru are on a boat on the water in the park. Rei tells him that they are tearing the park down to build a business district, and Mamoru says that people should take better care of nature. Ami and Usagi meet up in the park also. The old man is there and acting very strangely - he says that the only way for them to atone for their careless treatment of nature is with their deaths. Nephrite senses that his energy has peaked and summons the monster Petasos. Petasos steals the man's energy and he passes out, his hair turned completely white. Ami says this is unforgivable and transforms. After some prodding from Luna, Usagi transforms as well. On the water, Mamoru is weakened by a sudden headache. He and Rei get attacked by birds and fall into the water. Sailor Mercury and Sailor Moon are assaulted by butterflies (yes, butterflies are so powerful they can get in the way of both superheroes and a construction project) and Luna gets bitten by chipmunks. Sailor Mercury uses her Bubble Spray and weakens the animals. Petasos uses a Hand Flower attack and binds Sailor Moon and Sailor Mercury in vines. Rei and Mamoru make it out of the water but Rei senses an evil aura. As the monster continues to hurt Sailor Mercury, Rei appears as Sailor Mars and burns the vines off of the other two. With Sailor Mars and Sailor Mercury angry at the monster, they give Sailor Moon's speech using her lines. The monster sprouts more giant flowers for hands, but Tuxedo Mask appears and hits her in the face with a red rose. Sailor Moon uses the opportunity to use her Moon Tiara Action attack and defeat the monster. The old man goes back to normal. Ami tells him that he was only having a bad dream.
Mamoru walks up to the girls and Rei asks if he is okay. He says he is fine and Rei tells Usagi she thinks he is Tuxedo Mask. Usagi yells that there's no way, but Rei thinks that he has to be. Umino also walks up to them and tells everyone Usagi was on a date with him and that she asked him out. As her plan backfires on her, everyone teases her about Umino as she looks embarrassed.