Serena is late for school again, but Miss Haruna doesn't mind because she has a date with her boyfriend named Robert. However, when Robert phones and cancels their date, she gets angry and gives Serena detention for eating in class. When Ann insults poetry and speaks in an alien language, she also gets detention. They have to write a five-page essay. After Miss Haruna hears from Robert that the date was not cancelled after all, she leaves Serena and Ann to finish their essays, and they decide that whoever finishes first gets Darien.
Alan summons a Cardian named Insectia, but she refuses to listen to him. She jumps on his head and attacks a school, draining energy from many students. The other Sailor Scouts go after her. Seeing Miss Haruna and Robert, Alan tells Insectia to drain their energy, but instead she drains energy from ducks.
Meanwhile Ann is getting weak from lack of energy, and eventually steals Serena's energy. Luna informs Serena of the danger and she transforms into Sailor Moon to fight Insectia. Initially she is too weak to attack, but when the Moonlight Knight tells her to believe she has the energy, Sailor Moon destroys Insectia with Moon Scepter Elimination.
In detention, back in their original forms, Serena and Ann finish their essays at the same time.
- First and last appearance of Cardian Insectia.