Based on the Idolmaster Dearly Stars DS game.

Ryou has always had a problem with his feminine appearance. As a child he was often mistaken as a girl, and to his disappointment, that didn't change even after he got to high school. One day he came up with his best idea yet for gaining masculinity; he decided to become a male idol!

His cousin Ritsuko worked in the idol industry, so she was able to get him an audition. Unfortunately for his master plan, the company decided that he would make a wonderful female idol. Now, to even have a chance at becoming a male idol, he must first become successful as a girl!

The story starts off on a deserted island with a woman shouting "I ain't a chick!" while being chased by 100 male perverts in underwear!!!
Then it cuts back several hours earlier and we get to see how 'she' got into this situation.

It's a desperate struggle of survival on a deserted island between this woman and the different groups of men who are pitted against her, some of whom might turn out to be allies.

Junichi Sasaki joins his school's drama club upon entering high school. However, he soon finds himself dressing up as a girl for his first stage performance.

Iori is a timid, feminine boy. Masaru is an aggressive boy who leads the other boys in bullying Iori. One day, they encounter a pair of strange extraterrestrial bunnies who turn them into magical girls in order to fight aliens that are invading their town.

Himeno's chest hurts if any boy touches her because her heart is a diamond. However, when she was young, she befriended two boys--gentle Mamoru and blunt Keigo--who could touch her without harming her. Without knowing about her diamond, both Mamoru and Keigo promised to protect Himeno. When some people threaten to take Himeno's heart, who else will protect her but her knights?

"After losing a bet, Tao Nozomu's baseball team is forced to dress up as cheerleaders and cheer for their rivals, the Titans. However, after the bet is all settled and done, Nozomu finds he likes crossdressing almost as much as he likes baseball. Despite interior conflict with such desires, he tries to give it up; but one day, he discovers he's turned into a girl?!"

Having upset the president of the student council and embarrassing her in many different situations, Tsukasa is forced to do a small "punishment" by the president.

Part of Otoco Daughter Comic Anthology ~ Forced Hen ~

The best way to express oneself... created by the humanity is...Dance!

Yoo Myung-in, who never stood out, now goes on stage!

Daum Webtoon (Daum) Original webtoon (Korean webcomic)

Oneshot from NisiOisin and Kawada Yuuya:

A boy suddenly wakes up to find out he's in the body of a high School girl. Who is she and how did he switch bodies?

From Dazzling Scans:

When the masculine and popular-with-the-ladies Ooji Subaru arrives at her new school, her encounter with her childhood friend Megumi and the other four “princes” of the school leads to the discovery of her past life. She is the reincarnated Prince Charming, who was a womanizer who seduced all of the princesses in the land. As a result, a jealous witch placed a curse on him and doomed him to be reincarnated as a woman for eternity. In order to break the spell, Subaru must find the “princess”—now reincarnated as men—who is her one true love!

UB (Unlimted Blue), a legendary organization amongst the world of intelligence agencies. They do no belong to any country nor individual groups. Whether its the number of members or their whereabouts, all information about them is unknown. A secret organization known as the "other United Nation", sworn to protect this blue planet from chaos that threatens to destroy its peace.
The story unfolds around one of the top nine agents in UB, operative number 9, Code name: Musashi, and a young man named Shingo.

N/A

From xkazemg:

A slapstick/parody loosely based on One Thousand and One nights and other children’s fantasies. Princess Seblan was brought up as a prince to save her life… and she later turns into a real prince and lives happily ever after with his wife. Together with his sometimes-sarcastic magical horse Hendek, Seblan ventures out into the world of fairies, dragons, and other mystical creatures.

A collection of mildly ecchi otokonoko-styled stories focusing on crossdressing high-school boys and the boys who like them, mostly from the men's magazine Oto Nyan. Some of the stories are continued in Hiriajuu Shuudan ga Classmate o Josousasete Kanojo ni Shite Mita.

1-3. Raising Decoy
A boy helps his classmate go undercover in drag to catch subway gropers, and finds that he looks disturbingly good in a dress....

4. Ato no Matsuri (retitled Spilled Milk in the English edition)
A group of male students, having failed to get girlfriends, are becoming desperate; what will these "innocent" boys resort to?

5. Tenshi no Houbutsusen (Parabola)
Baseball-themed romance short.

6. Actress
A boy joins his high school's film club to meet the actress from their amateur film, but gets a surprise...

7. Shishiza no Boku to Natsu no Yozora (retitled Leo and the Night Sky of Summer in the English edition)
The president of the school astronomy club wants to catch UFOs.. maybe some "sexy female alien" costumes will help?

Set in early 20th century France, Claudine...! follows the story of a transgender man into adulthood. He struggles through life, being the first child after three older brothers to take after his father, and is constanly misgendered by those around him. He wants only to be able to find true love...

Included in Otoko no Ko Comic Anthology: Zettai Fukujuu-hen.

From Tokyopop:

Fujiwara Sunao is a rather unusual young lady. Not only does she prefer to wear her hair short and dress like a boy, but she also possesses the power to control water! One might think Fujiwara would be an odd fit at her school, but strangely, she's not. Between the destructive and demented school president, the kooky and somewhat stalker-like school nurse, and the obsessed underclassman who wants to be her apprentice, Fujiwara may be the sanest person at the school--which is a big help considering she may be asked to save it!

From MangaHelpers:
When an enemy explosion leaves private military soldier Terawaki Ryo nearly dead, a secret organization rebuilds his body using the research they have done in human revivals. Unfortunately for him, the technology only allows him to come back in the form of a teenage girl. His new identity, Shibahara Kyoko, leaves him distraught as his frail body doesn’t allow for the combat skills he used to have or even pick up heavy artillery he used in the combat field. Kyoko is assigned to protect a prestigious academy where daughters of powerful leaders attend since the girls’ presence makes it a hotspot for terrorists to attack and blackmail the people in power. Led by his former commander and mentor, Major Honjo who has also been reborn as Ryo, was a beautiful teenage girl named Chujo Shizuko, and the pair work together as anti-terrorist teenage school girls.

From Sweet Lunacy:
Who is the famous Rose Thief? Does Claude know who the maid (Christopher) really is?

From a_special:
The last scion of a fallen family enters a noble family's estate disguised as a female maid and must resist the amorous advances of his employer--who has secrets of his own!

At the peak of Beijing Operas, female roles were played by men. These men were required to have an excellent voice, postures and most importantly, beauty.