Stop!! Hibari-kun! Season 1 Our Merry Birthday!!

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.

A young man tries to flirt with Hibari, annoying her. Ibari believes men should wear loincloths, leading to another heart attack. The man introduces himself as Sparta Kotatsu, son of Tatsu the Spartan who went mad after losing against Hibari and became a cross dresser. As Kotatsu is quite perverted Ibari shoots at him with a machine gun, doubting he is the son of the highly disciplined Tatsu.

Hibari has a lewd dream about Kōsaku and decides she is going to steal a kiss from him. Kaji is jealous and sneaks into the Ōzora house but is caught by Ibari. Tsubame asks Hibari to pretend to be her on a date and reject Kaji for her.

Suzume invites her friends over for a study session, one of whom she has a crush on. Suzume's friends are initially too scared to enter after seeing Ibari attempting to remove Hibari's female clothing. Ibari puts on a play but the yakuza actors use real weapons so Suzume scolds Ibari.

Kōsaku wakes up from a dream of being unable to escape Hibari ending up as his girlfriend. He finds a postcard from his best friend and eternal rival, Daisuke Itagaki, who is arriving for a visit. When he first meets Hibari he refuses to believe she is his girlfriend and demands they prove it by kissing. Kōsaku wakes up from a dream of being unable to escape Hibari ending up as his girlfriend. He finds a postcard from his best friend and eternal rival, Daisuke Itagaki, who is arriving for a visit. When he first meets Hibari he refuses to believe she is his girlfriend and demands they prove it by kissing.

Hibari goes bikini shopping but Kaori arrives and steals a swimsuit Hibari wanted. As revenge Hibari collapses the changing room walls, exposing Kaori's breasts in public. Kōsaku and Seiji rush to save Hibari but she cannot leave the water as her bikini has fallen off.

Ibari refuses to allow Kōsaku and Hibari to go to summer camp. Sabu points out refusing to allow them to go would damage Ibari's yakuza honour. Ibari has a heart attack anyway. Shiina plans to seduce Hibari while Kaori plans to get Hibari.

Ibari is hosting the annual gambling tournament for every yakuza boss in Japan. Hibari hog ties Seiji and takes his place wearing a traditional yukata. Yakkun, the idiot son of the boss of the Crazy Group, falls in love with Hibari. Boss Crazy demands Hibari marry Yakkun or he will destroy her family.

Kōsaku has been having erotic dreams about Hibari and the lack of sleep is affecting his health. Ibari warns Hibari to leave him alone only to have another heart attack after Hibari accuses him of jealousy. Honda attempts to seduce Hibari but she rejects him just as Kôsaku and Shiina arrive to save her.

Seiji receives his very first love letter but is worried his job as a yakuza would make him an unsuitable husband. Hibari catches Kōsaku spying on them and drags him away for a date. Seiji leaves to meet Hanako, Kaori's friend who developed a crush on him.

Hibari and Kōsaku follow Tsugumi to a film set where she meets Takakura Yujiro, a young actor hoping to become a movie star. Ibari angrily tries to stop her but has another heart attack. In the end Hibari slaps Yujir unconscious and the movie director loves the action so much he makes Hibari star of his next film.

An earthquake during the memorial for Hibari's deceased mother unearths an old album containing pictures of Kōsaku's mother. Ibari almost burns the album but Hibari stops him. A politician asks Ibari for his help demolishing a children's park in order to build an entertainment centre.

Ever since he failed to seduce Hibari Honda has become afraid of girls. After seeing Hibari flirting with Kōsaku he decides to try seduce her again. Honda takes a picture of the pair together and spreads the rumour they are dating. Shiina becomes jealous so Honda's friends manipulate them into admitting they are not dating.

Kōsaku has a dream of being married to Ibari and having children. Don Corleone, a Mafia Don and old friend of Ibari's, visits the Ōzora house. Ibari forces his daughters to wear traditional kimonos then has a heart attack when Hibari also wears one.

Ibari, the PE coach is in love with homeroom teacher Iwasaki. Ibari decides to turn the house from a Yakuza stronghold into a family home. Yakkun, Boss Crazy's idiot son, attacks the Ōzora house with a tank.

Ibari takes Kōsaku to the Women's Wrestling Tournament. Ibari almost joins in but is caught by Chinma, the Wrestling Group President. Chinma asks Hibari to audition to be a wrestler. Hibari outperforms Rie at every exercise before they are paired up to wrestle each other.

Hibari tries to entice Kōsaku in her bra and panties, giving Ibari another heart attack. During volleyball practice the ball is knocked to Hibari so she returns it with a serve powerful enough to break the floor. Otori develops a crush on Hibari whilst dealing with her perverted brothers and eccentric mother.

The Ōzora family is having money troubles and many of their soldiers are quitting to find real jobs. Ibari refuses to change how he does business but is shamed when he finds a piece of Suzume's homework. Suzume defeats Ibari in a duel and demands to be made Chief Detective.

The Kurikara Detective Agency is asked to come to Monkey Island to solve a terrifying mystery. Another criminal tries to hijack the plane but is comically ignored as the Detectives and Ōzora's argue. Yukiyo disappears as an earthquake destroys the island freeing the Demon Monkey who returns the girls to their father.

Kōsaku and the Ōzora's end up stranded on a desert island. Ibari has a heart attack when he realises the natives can speak Japanese. They are joined by Kawahana Hiroshi, who makes adventure television programmes. He mistakes them for cavemen, only to be thrown into the river by the real natives.

Kōsaku learns. Suzume is frightened of festivals, and the upcoming Kotobuki Shrine Festival makes Ibari so angry he has another heart attack. Ibari fears that if Zenigame learns Hibari is a boy he will have Ibari assassinated. Tsugumi decides to play to get revenge against Umiushi's son, Bunta, for dumping her.

Ibari has developed a crush on Fumiko, a coffee shop manager. Ibari saves the coffee shop from being shut down by Coffee Ittosai by threatening to assassinate him. Suzume starts acting spoiled so Ibari slaps her. Hibari then offers to marry Ibari to shock him out of his depression.

While Suzume is on a date with Katagiri the park is invaded by child delinquents called the Kid Gangsters. Ibari forbids adults from participating in children's fights so instead Suzume has Hibari, Kōsaku, Seiji and Sabu scare the Kid Delinquents while she beats up Shadow Boss.

Kōsaku saves a girl from delinquent members of Kokuryu High Schools boxing club, until Hibari beats them up instead. A strange man harasses Tsubame and Suzume then breaks into the Ōzora house and peeks on Hibari in the bath. Private detective Shirachi Kogoro discovers Hibari is a boy.

Hibari and Seiji meet Kaneda Kanesuke, the brother of Kōsaku's mother, Harue. Ibari is outraged on his behalf that his uncle is a no good thief and scares him off. He then falls off the roof trying to escape Hibari's proposal of marriage.

Kōsaku dreams of becoming a Heian lord and Hibari a Geisha. Shiina arrives riding a bull so Hibari has Seiji throw the bull into the air. An ogre appears so Amachi has the entire city gather to hunt the ogre. Oni wants to return to his home planet but forgot where he parked his UFO.

Kōsaku and Hibari share a dream of marrying and winning the World Boxing Championship. They wake up and realise they have switched bodies. They consult an Occult enthusiast, Occult Ittosai, who informs them their souls have left their bodies. The only solution is to share another dream and return to the correct bodies.

Hibari and Kōsaku try to convince Tsubame to date Kaji, but she refuses as she prefers honourable men like Okita Sōji. Kaji's illness turns out to be a Coughing Bug that made Kaji cough whenever he got excited. Despite still being ill Kaji insists on fighting the final round of the match but cheats by claiming he has tuberculosis.

Hibari is possessed by white alligators that want to possess her, but she has a mystical barrier that stops them. She develops psychic powers as a result of the alligator's possession, including time travel. The episode ends with Hibari chasing Kōsaku who cries out "Stop!! Hibari-kun".