He became a magical girl, and his buddy fell in love with his magical girl form

Artist’s Twitter: https://twitter.com/isiyumi
Artist’s Pixiv: https://www.pixiv.net/en/users/1573847

This is the legendary Go Nagai's breakthrough work. Harenchi Gakuen is an elementary school whose teachers and students are all perverts. Boys peep girls changing. Girls pull up their skirts and show off their panties. Actually, it's not as evil as you imagine. They're like cubs playing together. It's only pre-school eroticism, nothing sexual. In spite of that, Harenchi Gakuen became a sensation. Parents, teachers, and politicians hysterically attacked the comic's immorality.

Hajime Nakano is forced by his mother to enroll at a newly opened all boys high school, and he laments over having to spend the next three years surrounded by other guys. However, he doesn't know that all of the other students are girls secretly pretending to be guys, and each of them think they are the only girl in the whole school.

Nishimoto Haruki is a 21 year old male and a newly recruited police officer. However, all his past assignments involved him dressing up as a girl in order to solve the crime. It seems that he has the feminine features that make him the only one suitable for the position. However, things get even crazier when he is assigned to be in the all female police squad surrounded by gorgeous women. He has to protect his secret that he’s actually a man but Haruki is already having a hard time controlling his urges.

The kingdom's hero, Ortus (♂), dies in battle after failing to fulfil a promise he made to protect the kingdom for the rest of his life. When he wakes up, he finds that he has been reincarnated as Seretina, the duke's daughter!

Even though she's a lovely, beautiful girl, she's still the same and determined to become a knight to protect her country in this life. However, besides being sickly and fragile, she is also faced with the harsh fate of a lady. She has to learn manners from her horrible mother, marry a man she doesn't want to marry, and many other challenges that will keep her from becoming a knight.

Then, on the way to the royal castle, a demon attack reveals her true power that no one knows about! A new heroine is born, with the strength to slay demons with a single blow, and the peerless beauty to captivate even people in high society!
She’s pretty on the outside, but fearless on the inside!
The chivalric, heroic fantasy of a feeble young woman begins!

An old man was laid off from his job at a black company. While wallowing in the depths of his despair, he encounters a mysterious stone that sends him to another world filled with magic and alchemy. The man finds himself reincarnated as Hiyo — the youngest daughter of the demon lord.

Hiyo attempts to make a dazzling fresh start in life by utilizing both her newfound magical powers and prior tribulations as a salaryman, however, the demon world is in the midst of a battle for succession. In order to change herself, the ex-old man is determined to defy the demon lord and her siblings. And after meeting Ernest, a hero with his own circumstances, they work together to take over the throne of the demon lord — for both the sake of peace and to search for a place to belong. The two of them defy destiny, even if it means destroying the world to do so...

From Easy Going Scans:

Chang An in the Tang Dynasty of China (618-907): The demon star is passing through the sky, calamity is about to befall the Tang Dynasty - because of a woman.
Skilled in martial arts and war tactics, Princess Li Chang Ge sets out to avenge her family and take back the throne.

“I hate men!”

Mao was harshly dumped by her boyfriend. She fell asleep while feeling totally dejected... and turned into a man the next day! Not knowing how to turn back, it was decided that Mao has to live in a dorm as a guy. However, her roommate, Ryuusei, is extremely curt and annoying.

How will her life turn out?!

With 99 nations conquered and the cup of the ruler in her hands… you'd think she was off to a heroic conquest, but the great queen's Cecia's real concern was her uncomfortable corset?

The queen of Valencia suffered from complicated laces and heavy corsets, and thus ordered her trusted brother, Duke Ennon Lionheart to bring her a comfortable clothes.

Meanwhile, Yuri, a clothing designer was killed in an accident after suffering from a small minimum wage at a medium-sized clothing company in Korea. She was reborn in a medieval country ruled by Cecia.

Yuri vowed to revolutionize the outdated clothing dilemma, so she dressed up as a man and worked as a designer at the top of the continent's highest court to do easy business.

But… what happens when Ennon discover's Yuri's true identity…?

Tatsumi enters highschool with his childhood friend Amasawa Kokoro, nickname Ama-chin, who is a extremely feminine looking trouser-wearing boy that likes to mess with peoples expectations of his gender.

Shinichi and Ichigo, who are childhood friends among their neighbors, are first-year high school students in the middle of their youth. There was a longing person who had a feeling for each of them! They couldn't get close to each other just by looking at their favorite person from a distance, but one day in early summer, a bitter gourd-related incident changed their daily lives.

I was cursed to become a woman in place of the prince, and then he proposed to me?! My best friend from childhood, the high-spec Prince Vincent, and me, his follower Renoa. Though I've always been a loyal yes-man… Even if you're taking responsibility for me, I can't accept that proposal! The infatuating love story between a troublesome prince and his scapegoat attendant!
Original Web Novel: https://ncode.syosetu.com/n1090ff/

Meguru Kaku is a normal high school student, except for the dreams he has about his previous life. One day, an unseasonal new student, Kotaro Kongochi, arrives. He is reunited with a friend from his previous life that he thought he would never meet, but something is wrong with him...?

A man is trapped in a loveless marriage. But as he is on verge of death, he suddenly experiences the medical phenomenon of a so-called "gender change". Reborn as a woman, his wife becomes his life coach.

A boy has become a magical girl, Kazana Sho is going to become more feminine to get stronger...

Naoki Tozawa is adamant in his aim to grow into a man among men, so he decided to go to an all-boys high school with a long history of providing strong and tenacious men for society. However, he is shocked and dismayed when he discovers that after a year of attending the school, many of the students have started coming to school dressed as girls. Rumor has it that the cause of this is a member of the photography club, leading Naoki to confront Ueda, a boy in the club who makes a very convincing girl.

To Chie Souma, a female college student, every day feels depressing when she has no luck with job hunting. She’d much rather end up in an alternate universe, just like in her beloved tripping into another world novels...... Just as she was dreaming of escaping this reality, one day she actually trips into another world! It might be too dangerous in a female body to survive in this world. Chie decides to use the knowledge that she’s gained from reading, lie about her gender, and become “Souma the scholar”, but---!? A manga adaptation of a strategy manual style fantasy.

A violent and muscular boy who dreams in becoming a national champion, unexpectedly turns into a cute girl, how will “she” achieve “her”dreams?

From Tokyopop:

In real life, Roto, Boromid and Ah-Dol are average kids with average problems, but in the virtual world of Lost Saga, they're heroes. They might even become legends... if they can stop bickering long enough to level up. Whether it's werewolves running rampant or a gorgeous pair of troublesome thieves, our boys must be ready for anything, because in Lost Saga nothing is what it seems and murder can happen with a click of a mouse.

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The series centers on the main character Jang-Gun and his friends along with their virtual reality avatars in the computer game world called "Lost Saga". When Jang-Gun logs on as a different character, he "Creates" an AI with a personality from the hacked disk he found when renewing his appearance for his once a year renewal process. Yureka is a flutter-brained, but advanced, AI with powerful stats and a real-life doppelganger. It is his turn to see just how deep his immersion in the virtual world goes.

Shizuku Ishiai, a 2nd year middle school student, loves dancing, but is bad at expressing herself, so she crossdresses and posts videos of her dances on the popular website "Smile Douga", under the alias "Ai". And she had declared the "dancing prince", Hayate, her rival. But, after a few unexpected events, and her attempts to best him, she's somehow thrown into an idol unit with him; furthermore, a MALE one?!