Bad Teacher's Equation, or "Kusatta Kyoushi no Houteishiki" in Japanese, is a 10 Volume Manga series with a 2 episode OVA adaptation.

OVA Left to right. Masayoshi, Arisawa and Inagaki.


It stars Atsushi Arisawa, a young man just starting high school. He has been in love with his tutor, "Ma-Chan" ever since he was little. He decides to go to the High School that Ma-Chan teaches at. Atsushi is in for a rude awakening when the man of his dreams, who was once kind and loving, becomes the total opposite and nothing like the loving Ma-Chan he once knew. Meanwhile, Atsushi's classmate and first kiss, Inagaki, is in love and after Atsushi.




The six main characters, nearing the end of the manga.Inagaki, top left. Yoriko, bottom left. Masayoshi, Middle. Atsushi, right. Tooru, top middle and Masami, top right.

Main CharactersEdit

Atsushi Arisawa

A new High School student, and the protagonist. He has been in love with Masami (Ma-Chan), ever since he was little. After finding out that the man he thought was Ma-Chan, was actually Masami's younger brother Masayoshi, he instead falls in love with Masayoshi and redirects his feelings towards him. Atsushi is very naive and happy go lucky, although as the manga goes on, he matures and becomes more serious and understanding of situations.

He is sometimes referred to as "Akkun".

He is 16, in the beginning, in the end of the manga, he is 20-21.

Masami Shibata (Ma-Chan)

Masami previously taught in a high school, but since retired, with his younger brother Masayoshi taking his place. When he was a teenager, he helped tutor Atsushi. Masami is kind, thoughtful and caring; while his brother is the complete opposite.
He is currently in a relationship with Tooru, and eventually the two get married.

Masayoshi Shibata

Masayoshi is Masami's younger brother and a nurse in the high school infirmary. He is the opposite of Masami, no etiquette, harsh attitude, no plans on settling down, party type.
He is very attached to his older brother Masami, who he was never separated from since childhood. But when Masami begins seeing Tooru, he feels threatened and scared to be left behind and was jealous of his brother's lover for gaining his attention. But eventually gets over it as he wants to become independent and let his brother have a life of his own with Tooru.
Masayoshi is very aware of Atsushi's feelings and sometimes uses his feelings to do better in school (Such as bringing him on a date if he gets a good score.)
For a short time, he dates a cross dressing girl by the name of Mizhua Toda.
He is 26 in the beginning, in the end of the manga, he is 30-31

Kouji Inagaki

Inagaki is very similar to Masayoshi, they're both harsh, rule breakers, the juvenile type. Ever since Inagaki had his first kiss with Atsushi, he has been head over heels in love with him and will do anything he can to get him. Inagaki does anything he can to get a kiss on Atsushi, to the point that it's just awkward and just doesn't work out.
His best friend Yoriko, is there to cheer him on.
He is 16, in the beginning, in the end of the manga, he is 20-21.

Yoriko Hayase

Yoriko is the epitome of a yaoi fan girl, she supports her best friend Inagaki, and will do whatever it takes to take a picture of two guys kissing, or any sort of romantic interest, even if it's Atsushi with Masayoshi.
It's later revealed that Yoriko is in fact, in love with Inagaki.
She is 16, in the beginning, in the end of the manga, she is 20-21.

Tooru Hagiwara

Tooru is the same age as Masayoshi, and upon meeting Masami, instantly fell in love. When Tooru found out that Masami was a man, it did not change his feelings for Masami. He is also a teacher at the high school, and frequently hangs out with Masayoshi in the teachers lounge. Before Masami, he did date a girl.

He is known as the bear, due to being excessively hairy, which is never shown in the anime or the manga, it's just said he is hairy. He is 26 in the beginning, in the end of the manga, he is 30-31

Minor CharactersEdit

Yoriko's Brother

Yoriko's brother is only shown during the basketball arc in the anime and manga, and in the manga when they graduate. Not much is known about him, except that he is on the basketball team and refuses to allow Inagaki to play on his team due to an event that happened when they were younger.

Atsushi's Mother

Arisawa's mother is a very kind woman, she likes to make treats for everyone.

Inagaki's Mother

Unlike Arisawa's mother, Inagaki's mother is mean and very harsh to Inagaki. Inagaki tends to refer her as the old hag.


Masami and Masayoshi's mother, she died when they were both young and while their father was away in Japan trying to start a business.

Yoshiyuki Shibata

Masami and Masayoshi's father. He loves his sons and is very happy when he gets to see them, although he is not happy when he finds out that Masami is with a man; eventually he comes around and even cries at Masami and Tooru's wedding.

He is close friends with "Yukio" (Or her stage name "Catherine"), a drag queen who still works at the club in Shinjuku.

Shibata's Grandmother

Masami and Masayoshi's grandmother is a wise woman, who despite the fact that she doesn't necessarily agree with Masami and Tooru's relationship. But gives her blessing anyways and actually mention that their father did a similar thing when he came home to propose with an already pregnant Leaf.

Takami Kenya

A young man Tooru befriends on his way to Norway, upon going to Norway, he tried to sleep with Tooru, however he declined. He reveals that he hates artists, this is actually do to his ex boyfriend, Karl. He appears once more, later in the manga and revealed that he almost slept with Tooru's younger brother.

He is 21, in Volume 3. Karl Klog

Kenya's ex boyfriend, turned back to boyfriend. He was a painter who would paint Kenya nude; after he fell in love with Kenya, he lost his painting mojo and dumped him. Kenya was upset saying he was the one that suffered the most and after a reunion, the two become a couple again.


Is her stage name, and sometimes called "Katrin", but her real name is "Yukio". He is a cross-dresser, who hates being called by his real name, Yukio. He is an old friend of Yoshiyuki. They once lived together after Yoshiyuki found Yukio in a pile of garbage, Yukio helped him out in many ways, such as starting the club in Shinjuku. It's hinted that Catherine, has feelings for Yoshiyuki, and refers herself as his second wife.


Another cross-dresser that works at the Shinjuku club.

Kyohei Hagiwara

Tooru's younger brother, he knows about Tooru being with Masami and is accepting of the fact. Kenya kissed Kyohei, and they almost became lovers.

Mizhua Toda

A tomboy who crossdresses; she works as model. Mizhua and Masayoshi date for a very short time, and it is revealed that Mizhua was actually arranged to marry Masami. When Yoshiyuki remembers that he arranged Masami to marry Mizhua, Masami refuses and chooses Masayoshi instead. Although Masayoshi and Mizhua hit it off pretty well, Mizhua decided to let Masayoshi figure his feelings out, and opened up to the idea of them being something in the future. But she hinted that maybe Atsushi, was the one for him and not her.

Tokiko Fukae

Is Mizhua's boss, and mentor. She wants Mizhua to act more like a lady and gives Mizhua more chances than other bosses would. It is revealed that she had dated Masayoshi for a while.


Tooru's girlfriend before he met Masami. In the present time, her and Tooru spend the night hanging out. They fall asleep in the same bed, and Masami comes to visit Tooru and assumes they slept together. In the end, Eiko clears everything up with Masami, saying nothing happened. Actually, she is engaged and was shortly leaving town.

Shinjuku ClubEdit

The Shibata's have a club in Shinjuku, mainly run by Masayoshi. It's a bar where many of their friends gather, mostly drag queens, cross dressers and other Queer people.


The cast go on vacation to a few places.

  • Japan, their home place.
  • Norway, Masami and Masayoshi's originally lived there for quite some time.
  • Hawaii, the crew go on vacation to Hawaii.

Running GagsEdit

  • There is one running gag where Masami and Tooru constantly get interrupted before they're about to kiss.
  • Tooru tends to end up in the dog house for saying the wrong thing, or gets too upset and worries about silly things.
  • Masayoshi getting a chill down his spine when Atsushi thinks about Masayoshi; the same happens if someone is talking about Tooru.


  • In the OVA, Atsushi gets kidnapped, Masayoshi and Inagaki rescue him. This however, never happens in the Manga and is one of the only big differences between the OVA and the first volume of the manga.
  • Despite the series revolving around Atsushi and his love triangle between Masayoshi and Inagaki, Masami and Tooru's relationship is shown the most.

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