Aishiatteru Kai (1989)

Ichiro Sato is about as average as a student can get... except for his above-average ability to land himself in totally awkward, intensely risqué situations with his no-nonsense teacher, Kana Kojima! Ichiro has his hands full dealing with these steamy shenanigans and unexpected encounters in the most unlikely places. At least it can’t get any worse, right?

There was a time when the Hachimitsu Private Academy was a revered and elite all-girls' boarding school on the outskirts of Tokyo but a recent policy revision is allowing boys into the student body. On his first day, Kiyoshi Fujino discovers that he's one of only five boys enrolled at the school. Completely overwhelmed by the thousands of girls on campus, the few boys find that their situation is less than ideal.

In this story, the world is in chaos, thanks to Washu. Now in order to save it, Tenchi Masaki must go undercover as a student teacher at an all-girls school. Unfortunately for him, trouble always comes his way as he has a hard time dealing with the hijinks of his new students.

Shiina Aki is constantly being treated like a girl due to his feminine looks so he decides to move to Tokyo to attend middle school in an attempt to change himself. However what awaits him in his new home, Sunohara-sou, is the kind-hearted caretaker, Sunohara Ayaka. Along with the three female members of Aki's new middle school's student council, Yukimoto Yuzu, Yamanashi Sumire & Kazami Yuri. And so begins Aki's new life in Tokyo living with 4 girls.

This is the story of a boy, who became the lone Adam among four billion Eves. In a world where a pandemic has rendered all men impotent, high school student Itsuki is the exception who escaped it. In order to protect this secret, he transfers to a very special high school, which turns out to be composed of 90% girls! There, he encounters an upbeat and friendly senior, a sexually frustrated female teacher, a tomboyish school 'prince,' and an heiress from a wealthy family. For Itsuki, who has his pick of any woman in the world, the question remains: which one will he choose?

Kagami Junichirou was known as a physics genius when he was a teenager, and he was even published in "Nature." However, after college, he suddenly lost all interest in science. As a NEET, he's devoted himself to his anime blog and nerdy collecting habits. He claims he has a serious illness called "I can't do anything I don't want to do." Desperate to get him to do something with his life, his little sister manages to get him a job teaching physics at his old high school. He's certainly an unconventional teacher, but he becomes fairly popular with the students. After helping a girl who's being ruthlessly bullied, Kagami finds that he actually likes teaching. Will he continue his career as a weird teacher? Will he go back into physics? Or will he end up back where he started?

Three couples, three intense romances: a student’s tutor crosses the line, a loner meets a force of nature, and a carefree man faces love he can’t ignore.

Naoya Mukai has loved Saki Saki since grade school, and when she finally accepts his feelings, he's at his happiest. But one day, a cute girl named Nagisa Minase confesses to him! Not wishing to choose only one over another, Naoya chooses to go out with both of them!! What will be of this love triangle that challenges morality itself?

Mizuki disguises herself as a boy and transfers to the same all-boys' high school her idol, Izumi Sano, a high-jump athlete who gave up on the sport, attends. In between their classmates' antics she tries to get him to jump again.

The story begins with Izumi Hayato running to be student body president. But when a beautiful girl swings in promising the liberalization of love while flinging condoms into the audience, he ends up losing to her and becoming the vice president. At the student council meeting, the newly-elected president invites herself over to Izumi's house, where she promptly announces she is to become Izumi's wife thanks to an agreement that their parents had made, a drunken promise decades ago that their children would one day become husband and wife. Naturally Hayato is against this, but Ui has the complete opposite reaction, and even wants to live with him! Will the upset Hayato and the overenthusiastic Ui be able to manage their school and marital life while keeping it a secret from the other students? Or will the two never come to understand each other's feelings?