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.

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.

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.

The manga is separated into 3 story arcs with close to none relation with each other's characters.
Volume 01-13: Video Girl Ai
Volume 14-15a: Video Girl Len
Volume 15b: Video Girl - Complete Story (about Video Girl Haruno)

Video Girl Ai [From Viz]:

High-school student Yota Moteuchi is so unpopular that his classmates have given him the nickname "Dateless." So it's no surprise when the love of his life, Moemi, is not interested in Yota but instead is in love with Yota's best friend, Takashi. Yota turns to a video rental shop for comfort, but little did he suspect that the shop was magical and that the cute girl on his rented tape would pop out of the television and try to fix his ruined love life!

Ten-year-old prodigy Negi Springfield, has just graduated from magic academy, and in order to become a master mage he is sent to Japan to teach English at an all-girls middle school. But Negi has a bigger dream than just becoming a master mage. He wants to find his missing father, "The Thousand Master", the strongest mage that has ever lived. And he soon finds that searching for his father wont be as easy as he first hoped. In fact, it pushes him and his students into life-or-death battles that decides the fate of millions.

Tokyo Swordia, formerly known as Tokyo Metropolitan, has been ruled by the "Swordie" since the Third World War 70 years ago. These Swordie, natural-born swordswomen with an attraction to blades, more or less rule the country, and are considered upper-class members of society.

In order to raise his own social status, Kurou, a human, begins attending an academy of swordsmanship, surrounding himself with Swordies on a daily basis. How will he fare in combat against those born to fight?

Aoshima Hitoshi is a second-year student in high school, who wishes he had a girlfriend. One day he wakes up for an unknown reason 10 years in the future, and he is married to the prettiest girl in school, Wagatsuma Ai! How has their relationship grown from mere acquaintances to husband and wife!?

Konoe Subaru, a classmate of Sakamachi Kinjirou, has been serving as the butler of Suzutsuki Kanade in school. Due to an accident, Sakamachi discovers Konoe's secret...that he is actually a she!? Apparently she will be removed from her position if anyone at school finds out. What will unfold from this chain of events?

She's a second-year high school student with a single all-consuming question: Will the boy she likes ever really notice her? He's the school's most notorious juvenile delinquent and he's suddenly come to a shocking realization: He's got a huge crush, and now he must tell her how he feels.

NOTE: Chapter 232 does not exist, there's no chapters missing.

Ichiru Kanzaki is given an offer he can't refuse: to clear his entire debt, he has to enroll in the high school where his father works to track down his father's illegitimate daughter, his own younger half-sister, whom he has never met. But which girl is she?

Eita enters high school aiming for the National University School of Medicine. Because of his parents' divorce--and his goal--he shuns anything to do with romance or love. One day Masuzu, the school beauty with the silver hair, who's just returned to the country, enters his life in a most unexpected way. Chiwa, his childhood friend since elementary school, will not let this go without a fight.

Hatsushiba Akira, an awkward high school senior boy, has a strong crush on classmate Sakuraba Yurika. But when he gets close to her, he always says or does something stupid.
At the suggestion of his best friend, Kikuchi, Akira enters the GachaGacha machine to play a game, but the machine fritzes out and malfunctions. That night, he sneezes while going to bed, and when he wakes up, he looks like the female avatar he saw in the GachaX2. He soon learns that sneezing will change him back and forth from his normal self to a female form. As a girl, Akira-chan is able to get close to Sakuraba and to become her friend.

Kahoko Hino is a student at Seiso Academy, one with an ordinary life. One day, Lili - the mischievous musical fairy who had blessed the original founder of the school - finds Kahoko running late to class.

Delighted that she is able to see him, Lilli grants Kahoko a magical violin, and a place in the school's annual musical competition, which many students in the music department vie to partake in.

Kahoko refuses, only to be pressed on by the fairy, who constantly nags her until she finally gives way to his pleading. She reluctantly accepts the instrument. As she practices her pieces, Kahoko is amazed that she can play any piece on the violin as long as she knows the tune and plays it with her heart. She later gets more attached to the surrounding boys in the competition.

Also contains the Kiniro no Corda 2 (La Corda d’Oro 2) and Kiniro no Corda 3 (La Corda d’Oro 3) stories.

Lately, Kouhei can't get his friend Kurara out of his mind. Even though he has known her since elementary school, all of a sudden, ever since she came back from summer vacation, he has been crushing on her... hard.

But something is different about Kurara--she's acting very oddly. Sometimes she seems wholesome, pure, and innocent, and at other times she is extremely forward and unabashed. Kouhei soon learns that Kurara has multiple personalities--and decides to help her keep her secret from their classmates. But Kouhei finds himself struggling between helping Kurara as a friend and trying to win her heart... which is a challenge, since she has many!

Sakurai Tomoki is a normal student whose motto is "normal is the best". If there is one thing abnormal, it is that he often dreams of a girl whose face he cannot even remember, and when he wakes up from that dream, he would always be crying. He tried leaving it as just a dream... but one day, from the sky, an angel descended.

A life description about the mangaka Aito Yuuki and his assistant Ashisu Sahoto.
Aito-san doesn't understand the feelings of the characters in his stories. So he asks Ashisu to help him. Ashisu would do everything for the work. She would even grope her own breast so he will know how it feels like?!

The Habit?! The Pervert?! Can we understand them? That's the comedy of a mangaka life.

Regular high-school boy Kaji Rikuo’s life is suddenly interrupted by a cute girl with cat ears named Vanilla. According to Vanilla, she was created from different mixtures of animals sort of like a chimera by her master, Ibu Kiriko, whom apparently has it out for Rikuo. Confused as to why somebody would want revenge on him, Rikuo become friends with the clueless and cute Vanilla. However, Vanilla can turn into a vicious animal able to hurt Rikuo with a simple command from Kiriko…

Despite her family's protests, Aoi Sakuraba decides that she is going to marry Kaoru Hanabishi, her love of eighteen years. Once he realizes that her intentions are genuine - and that she's not just trying to get him to reconcile with his estranged (and domineering) family - he begins to definitely warm up to the idea, too. What obstacles must the two overcome in order to be together?

From Baka-Updates: Aoi Kururi is an onmyou-ji who is studying smells at a private academy. He in fact hates using onmyou magic, but when a spell is mysteriously cast on his whole class that causes everyone to wet themselves, he finds that with the warm power and sweet smell of girls' urine, his magic becomes more powerful, and he saves his class by breaking the spell. This is the story of the strange misadventures of Aoi, his sisters, and his friends.

Daichi Kakeru is a peaceful high school boy who likes to collect cans. One day, when drinking a melon soda, a girl suddenly kisses him. The steel can transformed into a girl who wants people to appreciate cans more. Kakeru names the aluminum-can-hating girl Melon and decides to take care of her, but every time he drinks from her melon soda can, which is necessary for her survival, they kiss.

As he learns to cohabitate with her, their fun-filled days are interrupted by a government agency responsible for the economy, who not only knows their secret, but introduces them to the Akikan (Empty Can) Elect, where steel and aluminum cans fight in order to decide who gets manufactured for the market. While Melon is eager to prove the supremacy of steel cans, her Owner, Kakeru, is strongly against participating, due to an incident in the past involving his rich childhood friend, Najimi, and guns that made him hate violence. However, there are other aluminum cans who are just as ready to battle as Melon and when those two natural enemies meet, it is kill or be killed . . .