Talentless, shy Tsubasa has just been accepted into the prestigious Seiko Academy. He soon gets mixed up with the most popular kids in school -- and the entertainment world! Forced to join the pop idol group RINX as their lead FEMALE singer, Tsubasa soon finds himself stuck in the middle of a cross-dressing comedy full of mistaken identities, blackmail, and kidnapping!

Midori Yamate is a 15 year-old girl and is very much a tomboy. When she was young, Midori meets a boy called Tsukasa Hino, who came to the island she lives on for a holiday. He teaches her to play soccer and she falls in love with the sport. Midori is inspired by Tsukasa and continues to play soccer in hopes that they would meet again someday. When they do meet again Tsukasa does something unforgivable. Determined to defeat Tsukasa on the soccer field Midori enrolls in an all boy high school.

Contains a short story of 2 chapters called Shounen x Cinderella in the 8th and 9th Volumes:
Sakuragi Azuma has a secret that no one should ever know about: he's actually Momo Kasuka, an up and coming female model! While shooting a new drama, he meets another arising newcomer named Yui Hazuki, and things are going to get heated!

[From JanimeS]:

Dohun Yu has been living in England ever since his family collapsed. One day, Dohun comes to Korea almost forcefully without proper preparation. Don't ask me why, but I think it's his personality. (He does do things without planning anyway). Dohun loses his bag as he arrives in Seoul (the capital city of Korea) along with all his money. He comes completely moneyless within a day. A week later, he encounters an ad where it said "Seeking a friend! Paying well...yada yada blah blah, girl only!". Still having his suitcase which was confused with his sister's, he had girl's clothes. Having no other choice, he applies.

NOTE: This series was abandoned by the author at 4 volumes, with the story incomplete.

In the play of life, all Hikaru Takabayashi wanted was to be part of the scenery. Tormented by jealous schoolmates ever since she appeared in a famous commercial in grade-school, Hikaru transfers to a prestigious all-girls' academy where she hopes to settle down to a quiet life of anonymity. But when her new roommate turns out to be the super-popular TV idol Izumi Kido, Hikaru finds herself thrown smack in the spotlight's glare once more! And as if living with a celebrity wasn’t bad enough, Hikaru discovers that there’s more to Izumi than her “good girl” image—she’s a he! And this is only the first of Izumi's many dangerous secrets! Now Hikaru’s the unwilling star player in a madcap tale of deception, abduction, humiliation and blackmail...

This is the story of a boy who one day walks into some strange wood and is saved by a nymphomaniac godess who can not only take over his body (turning it into hers in the process) but can also transform him into a girl.

From StarryHeaven:
Jun has always liked the super popular and hot Kazumi-kun. However, he always has girls competing for his attention. So when the newest issue of a shoujo magazine comes out, she buys it for the furoku (freebie): a paper charm that you write your wish on and put under your pillow so that it’ll come true. Her wish? To be with Kazumi-kun. She doesn’t expect the charm to work anyhow, as she’s never had any luck with them. To Jun’s surprise and delight, in the morning she wakes up to find that she’s friends with Kazumi–but in a boy’s body!

Sixteen-year-old tomboy Ito Miura has become fast friends with her schoolmate and fellow drama enthusiast Makoto Amano. The problem? Makoto's a boy who must pass as a female drama student in order for his family to approve of his acting ambitions.

From Tokyopop:

Guilt-Na-Zan is a vampire aristocrat who was sealed into a cross by Kyouji's ancestor more than 100 years ago. Now Kyouji has revived him--although his soul was resurrected into a cute female doll and can only transform into his real figure when he sucks blood from Kyouji's sister Tonae. But when you combine Goth clothes and hot vampires, slowly but surely everyone will start to feel like one big family!

The story of two best friends -- a girl who's convinced that she's a lesbian because of her "non-girly" tastes and a guy who believes he's gay because of his feminine personality, and their search for love.

Yui has a complex about being so short, and it doesn't help that the guy she likes, Keiji, likes to poke fun at her for it. If that's not bad enough, why is the beautiful model, Rena, doing in Keiji's house?!

From Echochi Scans:

Ever since he was young, Mizuki's mother raised him up as a girl and forbade him from being close to other kids. Always dressed-up in a female kimono, this youngster is actually a successor to a wealthy clan. His mother hid his existence from Mizuki’s own father to prevent him from being caught in the crossfire of succession.

Appearing on behalf of Mizuki’s maternal father, young lawyer, Hatano tries to convince Mitsuki, who he first thought of as a girl to meet ‘her’ long lost father. This homosexual lawyer has some devious plan to use the female Mizuki to gain success for his own good. What’s worse is that Hatano is a frequent customer in Hanamai Koeda, the restaurant which Mizuki is working as his boy-self. Oh boy, Mizuki better watch out or his cover will be blown!

From Taciturnity Scans:

Ever since the day Ran Kurono's older brother, was killed while protecting Sei Ohtori, she has dedicated her skills and life to one day becoming the First Knight of the next head of the Ohtori family, even concealing the fact that she's a woman forever. For generations the Kurono family has served the Ohtori family as their First Knight, but 11 other lower knights with ill intentions of using the Ohtori family's authority vie for that title. Not only that, but Sei is being tested to see if she is suitable for having the title of head of the family. Upon entering Saint Locks Academy, the days of both Ran and Sei's trials begin, all the while being helped by Sei's untidy and unrefined fiance, Ibara Tennou.

1. Goshujin-sama to Atashi (Master and I)
Yoshinori got saved by classmate Sakura. Yoshinori's true identity is Yuki, a VIP fortune teller who has clients. In order to pay for her older brother's debt, Sakura became his bodyguard?!

2. Jingle Delivery: Santa-kun's Circumstance
On the path, a Santa Claus has fallen... and Atsushi gives this guy some food. Luckily, this Santa turns out to be genuine, and allows him to grant the wish of the girl he likes; the problem is, he'll take Santa's place if he doesn't grant her wish!

When his Handicrafts Club sempai, Himuro Saeji despairs of ever getting a girlfriend, Kirishima Hikaru is dragooned into helping out in a rather odd manner. Later he also goes "undercover" in practice for his starring role in the Drama Club's play during the school festival. From the anthology series Change H!

Car mechanic and ex-yankee Honda falls in love with Someya, a beautiful okama. Someya promises to go on a date with him in exchange for free car maintenance. Someya planned to tease him since the mechanic was unaware of his true gender, but when Someya reveals the truth, Honda's attitude doesn't change one bit! And now Honda's acceptance has stirred up feelings of affection in Someya!

18-year-old Mai Sugimoto is a college student starting this year. She was looking forward to the "college life," but she ends up living with two women because of a realtor's mistake. Furthermore, they are all 18-years-old and share the exact same name, Mai Suigimoto. Hence a life story of three Mai(s) full of fun and erotic excitement begins. Can these three girls get along?

A girlfriend decids to dress up her very effeminate boyfriend in a Yukata, but he takes it personal and accuses her of loving females only, and escapes to the fire work festival. Its a trap oneshot, gender bender fun, and the same author of The Night of the School Trip oneshot.

From Esthétique:

Ding Jiayu dreams of being a photographer. Her idol is none other than Yung Jo. When Yung Jo's photography company holds an audition to find a new photographer, Jiayu decides to take a chance. The thing is, Yung Jo's company doesn't hire women, so Jiayu has no choice but to dress up as a man and enter. Yung Jo takes great interest in Jiayu's talent and makes her his apprentice. It may seem like a dream to work with your idol, but for Jiayu, it's nothing of the sort. She takes a beating from Yung Jo everyday, and since all the crew members think she is a guy...

When Tae Yeon Im finds out that the idol star that she's adored for ages is currently attending the same school as her identical cousin, Jung-Woo Im. She convinces her cousin to exploit their similitude and switch places, or maybe he just likes wearing a skirt? So, she will dress as him, attend his school, and try to get close to her lover boy. Meanwhile, he will dress as her, attend her school, and revel in its sea of babes. The plan seems flawless until Tae learns of a bully named Ga-Wun Kim who likes to beat up on poor Jung-Woo. While Jung-Woo finds that being a woman might not be as thrilling as perceived.

From Shoujo Manga Maniac:

Ami has always been jealous of her little brother Chihiro, who's a popular model for girls' clothing. Now he's old enough to attend her school, and all the boys are crazy about him, even knowing he's a boy! Still, he's her brother and Ami loves him, but are her feelings for him beyond those of a sister for her brother?