From Forbidden Garden:
Manami, a highschool girl, joined the class party where there was fun, laughter, and drinking. She had the best night of her life until the next morning, when she woke up to find that she wasn't alone. She quickly looks over to see that lying next to her is her "friend" Motoyoshi Hajime. Did they actually do anything together?!! To the inexperienced Manami, her world is turned up-side down as she tries to figure out how to deal with this situation...

Includes:

1. Cherries Fight
2. The Fastidious Princess and the "Mature" Prince
3. Miss Pageant's Anego. Kakei Masumi ran an all-girl gang in middle school. Now in high-school she tries to bury her past, pose as a bookish honor student--and keep a tight leash on her temper. All this is at risk when Ohara-kun picks her to compete in the school pageant. Why her?
4. Secret Incompetent Swordman

From Tokyopop:

Naka is an aspiring young model with a problem: her face tenses up into a terrifying spectacle whenever she gets nervous on photo shoots! Naka's rival is Umi, the hottest model at their agency. But Naka soon discovers Umi's secret--and hilarity ensues behind the cameras!

From Aerandria Scans:

Young master Hewlett is a famous work-a-holic watch-maker whose one dream is to make watches only for people who appreciate and love them. And exactly when he thought he’d never meet such a person, his faithful butler Jill made him attend a tea-party where he met the new maid Mulara. And her first words were that her greatest treasure ever is one of master Hewlett’s old watches...

Tough, lazy, money lover, yet beautiful high school student named Shin Bia. While she's thinking about the eras she suddenly falls into that ancient time period! She had to transform into an elegant lady and while she's there she faces quite an obstacle.

Sachi goes to an all-girls high school, and is quite the clueless one. At her first goukoun, she meets a boy called Yuki-chan, which finally ends 17 years of a boyfriend-less life, and!? -- Manga Updates

Seda has it tough. Her school has suddenly gone from a girl's only school to co-ed. Plus, her father could be described as a Korean Scrooge.
But with the boys coming into her life, being late for the bus isn't the only thing she needs to worry about.

Sasami is the type of girl who gets easily pushed around at school. One day, a rambunctious young boy named Kou causes trouble in school and unknowingly drops a strange piece of candy. Sasami returns it to him, and he suddenly asks her to marry him! Will Sasami accept his proposal, or will she completely reject it?

Volume contains: main story (chs.1-3) + 3 oneshots

(from PocketScans)

From Esthétique: Rin is tomboyish 14-year-old who lives with her grandpa in a small village out in the countryside. After her grandpa's death, Rin is obligated to leave her village to live with her mother in Tokyo. When she arrives, she discovers an amazing secret: her mother is not an office lady, but a famous model called Myu Suzuki! After one night of reunion, Rin's mother leaves to follow some guy to some foreign country without any notice other than a letter. Without any money to survive on (her mom did not know grandpa died), and the contract between Myu and the model company, what is Rin is to do?

From Nagareboshi Manga:

Tsubame's school has two sections: the school for regular students, and a school for "celebrities" (known as the fine arts course, or the "celeb course"). Tsubame's stuck in the normal school, and has no interest in the upper class life. Then she meets Chio, a male model taking the celeb course. Her life will never be the same again.

Anise can't believe her luck when she finds herself in the same high school as famous former child star Siva. Although the cool and handsome Siva seems unapproachable, Anise manages to become his friend. But her happiness turns to surprise when she discovers Siva's secret: for years, he's been switching identities with his twin brother, Cipher!

Shin Gyu Yun is the heir of the Shin Oong Group and the self-proclaimed prince of Korea's economy. However, he has a secret. Since his father left them before Shin was born, he can't help but clean things due to his past of helping out his mother with the chores. It wasn't until that Shin's mother died in an accident that he came to know his scheming step-sisters by moving into his father's estate. The step-sisters conspire to make him lose his position... but could that have made him fall in love with a low-class girl?

Cute and child-like high schooler Suzu has an affinity with animals. She wasn't aware of just how much so until the day a large black cat literally falls into her arms! She wakes up after taking the injured cat home to treat its wounds, and finds a naked boy, "Noa" in her bedroom! He claims to be the cat, "Noir".

It appears that someone is after Noir as they are suddenly attacked by cats. Suzu can sense they are being controlled against their will. After their escape Noir/Noa is impressed by her bravery and the fact that she can understand animals--so much so that he asks her to have his babies!

Poor Suzu, what is she to do with this cat-boy who's determined to stay close to her, VERY close? And what of those who are just as determined to get Noir back?

From Manga Art:
Miyu, whose mom was chosen to be an astronaut, was sent to live with Kanata, a boy she just met. Soon after, Kanata's father leave the two to live alone. Amidst the panic, a mysterious UFO came... and out popped Ruu and his babysitter-pet Wannya. For the sake of Ruu, the four of them start living together......

When he was younger, Kujou Kiyosumi was incredibly awkward and nerdy. One day in elementary school, he courageously confessed his love to a girl, but she told him in front of the whole classroom that he was "disgusting" to be around.

Shocked, Kiyosumi asked the coolest guy in the class, Sagiya Maki, to help him become more likable, too. Thus began the days of training and now in high school, he had finally achieved most popular status alongside Maki. Everything seemed to be going along smoothly until...

Sumi is in love with Mitsuru, but he doesn't seem to be interested in her as a woman. Determined to look more sexy and mature, Sumi takes an experimental growth hormone that her scientist father has been developing. However, the medicine backfires. Instead of changing into a buxom femme fatale, Sumi changes into a beautiful young man! She--he--is so gorgeous and so cool that even Mitsuru begins to take notice. Although the new situation with Mitsuru is imperfect, Sumi discovers that she can be closer to her crush: they can talk man-to-man. Yet, being Mitsuru's friend also has a downside, particularly when he reveals that he is in love with a girl in his grade!

Seung Hun is a handsome playboy who's never experienced true love. Woo Sun is a charming playgirl who wants to be loved for herself and not her beauty.

Jong Yi is the beautiful, mysteriously childlike and vacant boy who becomes the object of their affections. A complex love triangle evolves between these three, further complicated by the involvement of Jong Yi's unfailingly devoted childhood friend and first love, a girl named Yu Ri.

They're all soon to discover that love is a long, painful path...especially if the object of it is completely oblivious to your attentions!

Note: As indicated by the genre tags, there are both shounen-ai and romance pairings in this story. It is not F/M romance only.

From Go! Comi:

When her grandmother passes away, high-school student Kajitsu Toda suddenly finds two hot stepbrothers and an adorable little stepsister dropped in her lap! Kajitsu and her step-siblings have only one thing in common: they were all abandoned by their parents. Against the odds, they've pulled together to form a family without grown-ups. They don't want charity, they don't want pity... they just want their dignity!

Things are particularly tough for Kajitsu and her step-brother Natsu. As kids, they were as close as any true siblings. Now, reunited for the first time in seven years, they've grown as far apart as two people can be. Can they ever become friends again? And can two high school students living together, even as "siblings" ever escape scandal?

A former prince and his retinue take Hifumi to a world powered by imagination.

Collection of crazy tales of love. 1) Electrical Shock Love Machine One of the most beautiful and popular girls in school, has zero interest in boys or romance. That is, until she meets Bansaku. He seems like a very average boy, unless one looks very closely... and Madoka does. She becomes so hypnotized by the little things about him that she loses her good senses, and when she regains them, she finds herself touching poor Bansaku, who has no idea what she's playing it! Madoka has spent her life dodging the unwelcome advances of desperate male love machines... Does Bansaku feel the same sort of disgust for Madoka's long-repressed, electrically-charged lust? 2) My Baby: Morimura Aki's handsome looks attract women by the thousands, but his violent manner keeps them all at arm's length. As an innocent bystander, Moe couldn't have cared less... until one of his outbursts led to her injury! Now revenge is a matter of pride. But when she exacts it, there's an unexpected result...? (No, really, you'll never guess if you don't read it!) 3) Like in Cinderella: When Chiyo lost her job and had to take on work picking weeds for the rich, she never expected to become like Cinderella. But when Yoshimune, the handsome young master of the Tokugawa Financial Empire, runs away from his "castle" with her, that's what Chiyo is certain will happen. But there's no guarantee that these two will live happily ever after, because this fairy tale isn't Cinderella's -- it's Chiyo's! 4) Don't Get Me into It: None of Ichirou's home tutors ever come back after the first tutoring session, but Takigawa Megu can't imagine why -- he's so cute! And... tied down in his chair!? It turns out that Ichirou is a complete and utter brat! Megu makes it her mission to prove herself superior to him, and Ichirou is actually impressed? Now, every time he gives her an inch, he gets her a little more into it. Before long, Megu feels like tutoring Ichirou... in the ways of LOVE!