From Shoujo Manga Maniac: Yuiri is a first year highschooler and the granddaughter of the principal. She attends Angelic Garden Highschool where she meets 4 handsome devils. It is her job to try and make these devils into angels. While in school, she goes under cover also as her brother Hairi. Can she persevere against these devils?

From ShoujoMagic:

Hatori is a tall girl who's easily mistaken for a boy, and she's in love with her childhood friend, Keishi. Even though he's a boy, Keishi is so cute that Hatori just wants to push him down and make him her own. Hatori has countless delusions and hallucinations (unbefitting a young lady) running wildly through her head every day -- and they're all about Keishi. They set her heart pounding and her nose bleeding!

From Tokyopop:

When Ami Won’s mother was still alive, she always told her to grow up to be an exemplary woman. And the chance presents itself now that her dad has been elected President of Korea. Thus begins this klutzy girl’s transformation into the girl her mother had always hoped she’d become.

However, in the spotlight and imbued with a kind of social power she never expected, Ami is now beset on all sides by the jealous and the dismayed. Her cousin Bi-Na leads this parade. Bi-Na considers herself naturally charismatic and infinitely more charming than Ami Won, so she feels she deserves the role as Korea’s First Lady.

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Girly boy Pil-Hyun Jung, also called Teddy Boy, strives to become a real man to win the heart of the girl he likes. He needs help becoming more manly so he becomes an apprentice to the author of a manhwa series about a pretty boy who wants to be a man. As Pil-Hyun works to overcome his problem, his love interest likes someone else, he gains a crazy stalker girl, and the women he lives with are all scary in one way or another. Will life ever go the way he wants it?

There is a pharmacy in this small town, whose owner never changes. The pharmacy has wondrous medicines that can cure every sort of malady? Even today, boys gripped by problems of love step through its door.

Mahoro Harukana moves to Tokio to achieve the dream of becoming an Idol. In order to do this, Mahoro will assist to the National Entretainment and Music School in Kamisaka. Everything goes surprisinly well, being great at singing and dancing, and even her teammates are astonished by her talent.

The only problem is that... Mahoro is actually a boy, and a boy who wants to become The King of the Idols!

In a time of swordsmen and honor codes, the most admired warrior is still unmarried. To keep him from falling in the hands of the wrong woman, his mother tricks him into marring her sister's son!

Neo Verona. A land floating high in the sky ruled by the Capulet family. That is until one night, when the long time rivals of the Capulets, the Montagues, storm the palace, killing the duke, his wife, and his men. All are killed but Juliet, a young daughter of the Capulets who is rescued and spirited away to safety before she could be killed. Fourteen years later, Juliet remembers nothing of her gruesome past, and lives with the small band who had rescued her, the only family she has. It is not safe for Juliet to go out undisguised, however, as a search for the Capulet heiress is still underway. So in public, she dresses as a boy, a young man named Odin, at the request of her "family". Though she is technically not allowed to, Juliet has another secret identity: The Red Whirlwind, the daring and righteous hero of Neo Verona, famous for saving any in danger with his (or rather, her) sword and advanced combat skills without killing anyone. It is on one of these "rescue missions" that she first meets Romeo, heir of the Montague house. By chance, they fall in love–a forbidden love that neither side will allow. Things get even more complicated, however, when Juliet finally learns of her true identity and is told that she must kill the current duke–Romeo's father.

From NOIR:

Lena Ha is a beautiful and a tough girl who is the captain of the kendo team. She meets Hye-Min Kang, the son of the president of a big company in Korea, and the two seem to fall in love at first sight.

But when Lena learns that she and Hye-Min are half-siblings, she runs away and falls into a strange body of water. When Lena wakes up, she finds herself in a strange kingdom...and learns that she may be its only hope. Now Lena, disguised as Ley, is ready for many adventures.

In 18th century England, Gabriel, an orphan girl from a fallen noble family befriended a young man named Jeremy, who was rumored to be an illegitimate child of a nobleman. After an incident occurred, resulting in his tragic death, Gabriel must impersonate her friend Jeremy, taking his place at an all boys academy for nobles, a place that may seem like heaven to others, but really hides a harshness which she would never have imagined.

From Divine Sanctuary:
Sapphire was supposed to be a tomboyish junior high school girl who's not interested in boys, but it all changed on her 14th birthday. Not only did she find out that she's prince Sapphire, the Ribbon Knight, but she also has to protect a country called Silver Land!?
Based on the original work by Tezuka Osamu.

Glen and Linus are orphans training to fight for a country on the losing side of a war. Glen has a secret that only Linus knows. Will Glen's secret stay hidden? And what exactly is Linus hiding?

A boy wakes up to discover he has become a girl! How will this affect his daily life?! A new one-shot by the award-winning author of Fire Punch, Fujimoto Tatsuki.

"What, isn't it fine to cling to you? As fellow models and girls." - "No... Though we're both models and girls... buuuut (>_<)"

Hinako has been a successful teen model for several years, when suddenly a new rising star appears: Mashiro Yuu. Cute, innocent and feminine - how can Hinako stay at the top of the fashion world? But what if the newcomer isn't what she seems to be..?

When his twin sister dies, a young boy decides to confess to the man he likes, but with a strange twist.

A collection of oneshots:

From A Willful Muse & Alice Dreams:

"Wanna book a room with me?” It was only meant to be some harmless teasing! Aoi’s never even had a first love but now a mysterious boy has accepted her joking offer seriously. From a misunderstanding, Aoi and the boy start a passionate relationship. It’s only physical, right? Or has Aoi unconsciously started to fall in love with him?

- Tengoku No Tsuki - At an all girls school, Yuuri is the idolized, boyish and tall, upperclassman. With rumors of the "Perverted Hand" flying about the school, what will Yuuri do when her best friend is the next victim?

- (Chapter 3 continues Tengoku No Tsuki) Protecting Eien's secret and granting his happiness is Yuuri's main focus of her beloved. But how will Eien react to the Priest getting too close to Yuuri during the school play?

- Vampire Lover - Saku Mikuriya's parents divorced and she was left to live with her headmistress grandmother. As she cried of how she was unwanted, a man with golden hair and golden eyes appeared before her. "Then do you want to leave with me?" he offered, they made a promise when the flower blooms, he would come and take her away. 10 years have passed and the flower only buds, but what happens when a mysterious transfer student arrives and he looks exactly like the man she met 10 years ago?

- Nana is ordinary, plain, doesn't stand out, and totally in love with Shu Aiba, a model and her classmate. What happens when Shu picks her to be his "girlfriend" for his "Tropical Island Vacation with My Girlfriend" shoot?

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From Viz:

Megumi Amatsuka, a rough and tumble nine-year-old boy, always dreamt of becoming the "manliest man on earth." Upon receiving a book of magic from a sorcerer whom he saved from a group of local thugs, Megumi summons a genie in order to make a wish. But due to a sick twist of fate, the genie turns out to be an evil one, and Megumi winds up being the "womanliest woman on earth"! Six years later...Megumi is the most desirable girl in school, but deep within her hot-mama façade is the same trash-talkin', punk-stompin' boy.

From ShoujoMagic:
There is a legend in the kingdom of Paros -- a legend of the Sword. It is said that if one who is unfit to rule should wield it, it will mean the ruin of the kingdom. As sole heir to the throne of Paros, Princess Erminia must accept the Sword and a husband when she comes of age on her next birthday. But the princess refuses to wed any man who is less of a man than she -- which excludes every man in the kingdom! Just when Erminia is ordered by her father the king to wed her foster brother Yurias, she has a fateful encounter with the unfortunate, beautiful maiden Fiona..!? "The Sword of Paros" is a miraculous romantic fantasy about defying convention, transcending gender and status, and knowing oneself.