Mitsudomoe

Newly hired teacher Satoshi Yabe begins his job teaching class 6-3 and soon becomes aware of the terrible Marui triplets, Mitsuba, Futaba and Hitoha. When the triplets notice Yabe might have a crush on the new school nurse, Aiko Kuriyama, they purposely try to injure his groin in the hope that Kuriyama will like what she sees. When Yabe incidentally gets injured after running into Kuriyama, she confuses him for a fourth grader (she's blind without her glasses). Yabe gets the class a pet hamster, which Hitoha names Nipples and becomes attached to. When others start to play with her too much, Hitoha starts becoming defensive.

Futaba catches a cold and ends up ensnaring Yabe into a rather long and sticky booger. Hitoha gets access to Yabe's apartment in order to see Nipples outside of school, blackmailing him from making other arrangements.

A boy named Yuudai Chiba catches a glimpse of Hitoha's erotic book and wants to see more of it, his friend Shinya Satou getting confused and assuming she wants to see her panties. Through certain events, Hitoha ends up meeting occult fanatic Sakiko Matsuoka, who mistakes her as being able to see ghosts. They end up sneaking into the pool before it opens, with Sakiko assuming Hitoha is trying to exorcise spirits, when she is actually drowning. During swimming the next day, the triplets forget their underwear and jump to the conclusion that they were stolen. When their suspicious looking father, Soujirou, arrives at school with the panties, Mitsuba is too embarrassed to admit losing them and implies he is the thief, getting him arrested.

The series begins with an episode of Serious Sentai Gachiranger, in which the evil Gedol Empire try to eliminate children from the Saitama District so it will be easier to invade, using a monster named Crabron to turn everyone into a pile of bubbles. The Gachirangers hear about this and set into action, but seem to screw up at every opportunity. The Gachirangers later confront Crabron, culminating in a giant robot vs. monster duel. Upon defeating him, all the children return back to normal. Meanwhile, Hitoha is frustrated that the episode was filled with a lot of stupidity compared to the usual.

While protecting a photo she took with a Gachitanger, Hitoha inadvertently sparks a rivalry between Sakiko and the Hopeless Squad. Mitsuba desires an exercise machine and uses Futaba as a replacement. Yabe tries to work up the courage to ask Aiko to a Christmas party, but she loses her glasses and starts wrapping everyone wearing red clothes in bandages. Yabe ends up spending Christmas alone while Yuki holds a mixer party, though no one seems to go with her ideal picture of the King game. With Souijiro coming home late, the girls get Yabe to fill in as Santa for Futaba, though she ends up gripping tightly on his clothes, putting Yabe in a rough situation when Soujiro comes home.

Futaba decides to draw an erotic manga for Yuudai, roping in Shinya to help her learn to draw underwear on her figures. The school practices a fire drill, with Yabe's imagination getting the better of him. During a sports event, Soujiro ends up losing his clothes in preparation for a three-legged race with Hitoha, landing him in an awkward predicament. Yuudai invents a new move to unhook girl's bras, which leads to various misunderstandings while trying to find someone who actually wears a bra. While over at the Marui house, Mitsuba's friends find an old photo of Soujiro when he was more handsome, with Mitsuba claiming him to be her boyfriend.