From StarryHeaven:

Anjuu Sendou is a nice girl who just started her first year in the Seiryuu Academy Middle School. She is currently living away from home as a boarding student with her pet named Lime. Her father is a sorcerer and her mother is an expert in Chinese kenpo. They are both famous, especially her mother who is called Dragon Momoka.

Because of her mother’s fame, the executive committee wants Anjuu to join the student council. But the council’s president thinks that she is a weak girl, so to prove him wrong she decides to catch the school thief. When things get difficult and she wishes to become stronger, her pet suddenly transforms into a small child with wings (a pre-dragon form, because Lime isn't fully grown) and tells her about her power.

The next time the school thief appears, Anjuu, with the help of Lime, transforms into a new Saint Dragon Girl, defeating the enemies and becoming the school’s protector. Will the student council’s members find out the true identity of the warrior girl? Will Anjuu be able to keep her secret?

From Hoshi Kuzuu:

Out of the blue, childhood friend Takaoka confesses to Iwami! When popular playboy and ladies man Takaoka says "I love you", he doesn't believe it one bit. Is he making fun of the virgin!? A modern high-school boys' adolescent love development!

Honjou Naru is an 18-year-old young man studying at Libre University. For his entire lifetime, he never once had a girlfriend. This is because of his abnormality, his narcissism, which only happens if he sees a reflection of himself. To prevent that, he needs to wear contacts all the time. One day his contacts fell off and was step on by the most handsome guy in the school, Takashina Mamoru! This chance encounter would change his life forever...

From Viz:

Haruna Aizawa thinks that school life is just like a monkey mountain--all the monkeys form cliques, get into fights, and get back together again. The school that she just transferred to is no exception. There's even a boy called Macharu Yamashita who reminds her of a baby monkey!

From Eclipse Scans:
A school where the students make their own riches. From Models to Computer Geniuses, These students get rich on their own.
Namu goes to a school where all the elite get idolized by the non-elite. Never making it easy to get to school on time, Namu is soon helped by a new transfer student. Who gets categorized as an elite almost immediately?

Kaguya is a boy in an all-girls' school for demons [fox spirits, succubi, werewolves, etc]. Being the only human is bad enough, but the added risk of his manhood being discovered makes for silly and unbelievable (deliciously enviable) situations.

Yamanobi Apartments have a story behind them: Anyone who lives there will gain something big, but lose something big as well. This is a collection of stories about the various tenants and their love lives.

1) Muroi Kaname has just moved into Yamanobi. The naturally unsocial Kaname doesn't care about stories, and also quickly manages to alienate himself from everyone in the building. But when his upstairs neighbor, talkative Fujimura, sees a different side to him, he's determined to be Kaname's friend. Kaname slowly lets himself grow closer to Fujimura, but will their friendship withstand the jinx?

2) Kamimura Mizuki has always chosen lovers for their looks, and gotten nothing but trouble. This time he wants a sincere guy, and he already has one picked out: Itokawa from his work. But getting his attention is proving to be somewhat difficult. At least slacker apartment caretaker Akabame always listens to his troubles...

3) Nojima is known as the life of the party, always light-hearted and in a good mood. But he's really a bundle of insecurities! He's hiding a secret love for cool classmate Kariya and has moved into Yamanobi for the jinx. But his secret love is slowly turning him into a stalker!

extra) Kanata has been in love with Soejima Ibuki for two years now, but he always sees Soejima-san with a new partner. Will Kanata be able to tell Soejima how he feels or will he suffer with an unrequited love forever?

extra 2) 3 short comedies on the residents of Yamanobi Apartments.

Werewolves, demons, monsters, vampires. All these ferocious creatures are afraid of the same thing: the beautiful Princess Hime, an awesome warrior who fights off the forces of evil with a chainsaw and a smile. Not only does she look great in a tiara, she has power that allows her to raise the dead. She's a girl on a mission, and with the help of her undead servant and a supercute robot, there's no creature of darkness she can't take down!

Always a very tall and stern man, Matsudo has recently joined the student council as the treasurer. To his distress the rest of the members of the student council are nothing but extremely gorgeous and lazy girls... Will he be able to say "no" when they ask him to do their work for them?

High schooler Jenny You is living a dream. In the public eye, she is a delicate princess, a successful pop star, but in real life, she's a rebellious beauty ostracized by her female schoolmates. She and her classmate, Eumpa Won (One), seem to have nothing in common on the surface. Eumpa is a quiet boy, ignorant of the pop culture that has enchanted most of his peers. Having spent his childhood as a depressed prodigy in the United States, he has now resolved to lead a normal life as a regular boy. He likes a cute-but-average-looking girl, Young-ju Chae. Young-ju takes him to a pop concert, and Eumpa is exposed to Jenny's music for the first time. Meanwhile, umpa's resolution to live a normal life is challenged when his music teacher steals the young man's music and attempts to pass it off as his own... So begins the story of One...

The story sets one month after Eita and Masuzu start dating, and sets itself on a "what if" scenario where the Harem element is stronger than in the original.

Otokojuku - a private school for juvenile delinquents that were previously expelled from normal schools. At this school, Japanese chivalry is taught through feudal and military fundamentals. Similar to an action film, the classes are overwhelmed by violence. Only those who survive it become true men.

from Renta!

From Intercross & Shoujo Crusade:

Chika has always seen Murasame-kun as a rival who manages to constantly piss her off. While wondering out loud to herself, her sister whom overhears Chika, gives her a perfume necklace which supposedly able to capture a guy's heart. The next day, Chika bumps into Murasame-kun and spills all the perfume. As she begins to apologize, he suddenly asks her out?!

From Anime Waves:

Meet Shizuki Maku - to say she looks "above average" would be a slight overstatement, but it's especially bad compared to her older twin brothers, the high-school heartthrobs Retsu and Tetsu. She always wondered whether or not she really belonged in her family, but things take a shocking twist when her brothers plant the suggestion that they may not be related after all.

Now she's supposed to pick one of them to be her boyfriend, all the while defending herself from all the other girls at school who want to keep her "brothers" for themselves! Life isn't easy when you're the ugly duckling!

Sonnan Ja Nee Yo received the Shogakukan Manga Award for shoujo manga in 2006.

From Shoujo Crusade:

Miyako's living her life diligently following rules, just as her deceased father wanted her to. But one day Azuma Koutarou sees her play guitar and blackmail her to join his band. How will she face it up?

There's also three extra stories that are unrelated to the main one.

Tatsuhiro moved to Tokyo to attend an art school and start his new life. In his new room, there’s a small hole in the wall. At first he can see nothing through the small hole, but one night, through the peeping hole, he saw a girl. That’s how his new life starts.

For fighting and humour fans Jo Pae, a not really sane boy, in our modern days, he wants to become emperor of Korea... His first step when he enters high school is to become the leader of the strongest school there is. No one expecting it, he actually takes down all of the school's yankees. Jo Pae is now the enemy to kill! All rival schools wants his head whatever the means!

Without doing much research on the school or surrounding areas, Hibino Ryouichiro picks an art school in Hokkaido. Tricked by the school advertisements, he goes to the campus only to find out it is a desolate and cold campus. The only glimmer of happiness for Ryouichiro are the girls on campus. Just hours after meeting Kisaragi Riho, the cute girl on campus, she seduces him only to find himself outside naked after she is done with him. Feeling heartbroken and used, he finds comfort in Aso Tomoe, who lives on the floor below at the dorms. Although it is freezing outside, it is hot underneath the sheets for Ryouichiro.

Rinne, a huge fan of Buddhism, was searching for a "monk-type," a boy as calm, intelligent and diligent as Lord Buddha himself, when she set her sights on a young, handsome monk-in-training, Yuuryou. She soon learns that this kid, out of his robes, is not her dream boy, but a shallow, irresponsible lady killer who goes by Yura. Is Rinne going to give up on her fantasy, or is there more to Yura than meets the eye?

From Shoujo Crusade:

1-3) Lovers in Conflict
Because of her sister who suddenly ran away, Sagiri ends up getting married in her place. Her husband is hard to understand and is a bit of an S. What will happen to their married life?!

4) Wild Rose's Crown