Kang Ji-hoon, an ordinary high school student who died in a painful accident, finds out in the underworld that he is actually a ‘Water Spirit King mistakenly born as a human’. “Making water spirits? How do you do that?” The adventures of Elqueeness, the Water Spirit King who was mistakenly born as a human!

Mitsuki Kou is such a feared PVP gamer that he's earned the nickname "Crim the Headhunter" in some circles. His next game to take over? "Destiny Unchain Online", a brand new VRMMO game developed by none other than Kou's father. But, no new game on release day is without its bugs - namely, Kou glitches to the middle of nowhere, and his vampire avatar is turned into a girl! A story for all of the people who through games have met new friends and aimed for the top... start!

I was reincarnated into the body Cecilia Silvie, the villainess of an otome game.
According to the plot, what awaits me in the normal route is either a slow, painful death or an instantaneous one... Essentially, every route leads to my demise.
Then I'll change my fate! And that's why I decided to become a man.
However, I made a mistake during a certain event, and the story began to head down an unexpected path...?

A young girl fights on the frontlines in war. She has blonde hair, blue eyes, and nearly transparent white skin as she flies through the air and mercilessly strikes down her enemies. Her name is Tanya Degurechov and speaks with a young girl's lisp while she commands the army. Tanya used to be one of Japan's elite office workers, but because of a wrathful god was reborn as a little girl. Prioritizing optimization and career advancement above all, she will become the most dangerous entity among the Imperial Army's sorcerers.

Stories following various adolescent girls and their encounters with puberty and other worlds.

An old school yakuza, Nagamasa Ryumatsu, ended up losing his life due to certain circumstances. But, when he awakened to a strange sort of scenery he had never seen before, he found that he had somehow changed into a beautiful girl!?

While cross-dressing, I was hit on by a handsome guy, except she wasn't actually a handsome guy!

Albright, who was famous as “the strongest Black Knight”, was reincarnated as a girl, Maria, whose ribbon suited her well for same reason. Maria, 16 years old, is currently a maid in the Marquess of Urband family in attendance to the Daughter of the Marquees, Relena. After Relena became engaged to the 4th Prince, the area around Maria had gotten busier…

A hitman and a marriage swindler set out on the world’s most grueling battle for marriage! Gero is a young man from a clan of hitmen, which has been in existence for hundreds of years. As someone who’s never gone to school and lived his life dealing in the dark side of the business, he considers himself to have “no prospects with women” and marriage as “something not for him.” However, one day, in fear that their lineage would dissolve, his clan warns Gero that if he doesn’t marry and produce an heir, they would have no choice but to…force his little sister into doing “that.” Driven to his wits’ end, Gero asks the target of his work, a marriage swindler, to…

Misaki-kun may be adorable, but he's just the 'best friend' type character you can find in any gal game. However, the protagonist, Kihara Hareta, isn't set on wooing any of the heroines; he has his eyes set on the Unobtainable Misaki-kun! Gender makes little difference in the face of such cuteness in this heart-stoppingly sweet comedy!

From MangaHelpers:
Nogawa Izumi is a good student, and a class representative, but she has an increasingly high libido. It's gotten to the point that she'll claim to feel bad during class, so she can run to the nurse's office and masturbate. When she learns that the Earth is being invaded by aliens that look like people dressed up as animals, it turns out her high sex drive may be able to help protect the Earth. The first time Izumi is attacked by the aliens, she is rescued by Usayama, a bunny alien whose race was their previous victim. Usayama gives her a swimsuit that will allow her to fight the aliens, but which also sends her constant arousal through the roof. The scientific organization that Usayama is affiliated with think that Izumi, with her high erotic level, may be the person they've been looking for to fight the aliens. Will Izumi be able to save the Earth?

Uesugi-kun is a boy who's as petite and cute as a girl. He has a crush on a girl he's known since childhood, but overheard her saying, "Wouldn't Uesugi be totally adorable if he was a girl?!" Uesugi-kun's not as tall as his other childhood friend, Eito, nor is he as good at studies, and now he's suffering from a broken heart. A depressed Uesugi-kun stops by a shrine while running an errand and makes a wish... A love-triangle romantic comedy featuring an overly cute, and now female, protagonist begins!

Rin's village getting attacked by bandits doesn't keep her down in the dumps for long! Picking up a sword housing an extraordinary pervert… I mean hero, Siegfried, she sets off on a journey of many bouts with various degenerat… ahem, heroes!

As the master of the School of Unholy Arts and as the undefeated Unmasked Demon, MookHyang unfortunately falls to a strange fantasy world by the magic of his enemies (School of Blood Arts). In the new world of elf, sorcerer, knight, and dragon, MookHyang’s adventure of finding a way back to his old world (Murim) unfolds.

"Haruka Yamagishi" is a guy who has no friends or family and just goes back and forth between work and home. One day, when he wakes up, he finds himself in a different world. And for some reason, he's turned into a beautiful dark elf! Now, Haruka has inexhaustible magic power, a sturdy body, and a new life where she can do anything... However, through the friends she met and her activities as an adventurer, changes slowly began to take place. The guy who gave up on life in this world begins to feel what it's like to live. Although there are some traps and other events, it's a touching adventure story!

[Source: Manga updates]

Both of them are straightforward people. Once they meet, they quickly get to know each other better. A heartwarming romantic comedy that begins with a certain incident. Shibata Kasane, a graphics designer at a toy design and development company, is troubled. Her troubles started when she grabbed her colleague Enokida Subaru's ass by accident! Kasane was intrigued by how similar Enokida's ass and her favourite childhood character felt. At the same time, Kasane felt guilty because Enokida might have been uncomfortable. Enokida said "I don't mind" but had a pained and frightened expression. Kasane was overcome by the urge to apologise profusely! On the other hand, it looks like Enokida is hiding something.

Although she had been a promising practitioner of kendo in the past, due to an accident she was forced to lead a plain life. After Seo Yuri gets into a car accident during a trip back home, she reincarnates into the novel, "The Song of the Moon," and becomes the elder twin sister of a side character who meets a destructive ending-- Selena. Selena hopes to prevent the destruction of her family, however, she is forced to take the place of her runaway brother, Celestine, in the knights’ squadron! Will she be able to avoid the villainous Crown Prince, Ignis, and survive?!

High school student Boji Nichiro is isolated from the rest of the world due to fierce bullying. One day, however, the world is transformed by the "dungeonisation" phenomenon! In the midst of the chaos, Nichiro awakens the unique skill "Shop". It was an out-of-the-box skill that allowed him to buy everything from food and daily necessities to unrealistic items! The start of a painful and "wacky" modern fantasy from "Shosetsu-kaerou"!

Marimo Himenogi desperately wants to become an idol singer. When a local contest is announced, she begs her boyfriend, Ayumi to sing as her partner. Ayumi relents, and disguises himself as a girl so that he and Marimo can enter the singing competition. Surprisingly, they win and are signed to a recording contract as a new group called "Twinkle". Now they must keep their newfound fans from finding out that Ayumi is actually a boy.

Bi-Kwang is a handsome young warrior who becomes a drooling mess whenever he sees a pretty girl. Out on the road he meets an extraordinary swordfighter with no name who is searching for a legendary master warrior. Bi-Kwang promises to aid the swordfighter if he lets Bi-Kwang meet his beautiful sister. Of course, it turns out the swordfighter is the sister, Hwa-Rin Dahm, and she must switch identities to keep the plot moving along. Bi-Kwang is immediately smitten, and thus we have a triangle involving only two people.

This manhwa was made into a MMORPG.