Stop!! Hibari-kun!

Following his mother's death, high school student Kōsaku Sakamoto moves in with the yakuza boss Ibari Ōzora. He initially believes Ibari to have four daughters, but is shocked to learn that Hibari was assigned male at birth. Everyone at school believes Hibari is a girl because she looks and behaves like one.

After having a nightmare where Hibari kissed him, Kōsaku is woken up by Seiji, an intimidating underling of the Ōzora Group. Ibari sees what he thinks is the two sleeping together, causing him to have a heart attack. Tatsu believes if Hibari were to ever act like a man she would be an incredible yakuza.

Hibari dresses in punk clothing to sing for a friends rock band during their school's foundation day. Ibari freaks out when Hibari asks to be treated as his daughter and has another heart attack. Back at home, it is revealed that Tsubame dressed up as Hibari and went to school in her place.

Kōsaku has a nightmare of himself as an ant being targeted by a "horned" Hibari. As Hibari is getting dressed, Ibari barges into her room to confiscate her female clothing. Tsugumi believes Hibari being around Kōsakau has made her even more feminine. He plans to become manlier to repel Hibari's "perversions" and visits the school's boxing club. Hibari defends him by knocking Mitsuo Kaji unconscious in the ring.

Hibari prompts Rie to tell Shiina she loves him while Shiina plans to kiss Hibari. Kōsaku almost reveals Hibari's gender but is stopped by her before he can. Rie asks Hibari to come with her to the baths as she is scared to go alone. Seiji drives the club to the camp, with Hibari and Rie sharing a room.

Tsugumi has recently fallen in love. Ibari does not approve as her boyfriend, Bunta, is from the Umiushi family, the Ōzora family's traditional enemies. Hibari suggests Tsugumi and Bunta pretend to commit suicide, Romeo and Juliet style, to change their parent's minds. They decide to elope instead and are caught by Ibari wielding a shotgun. Bunta flees while Hibari defeats Ibari in a shootout. Days later Bunta marries a rich businessman's daughter instead.