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

Imagine a senpai you don't get along with. Then imagine having to work with and live in the same apartment as him! With no vacancies in the single's dorm, newbie cop, Kaitou, has no choice but to move in with his senpai from the koban, Himuro. While he's beautiful and excels at his job, Himuro has a mouth on him and he and Kaitou fight like cats and dogs. But then one morning, surprise! A sudden embrace and a kiss!

"Give me back my first kiss!" Romance, trouble and a love triangle. A fiercely tsundere senpai versus a hot-blooded rookie equals a workplace romance!

Vampires have evolved and don't rely on human blood anymore. They now co-exist secretly as normal citizens even though they are still feared and discriminated against by the society. So what happens to a female vampire trying to live a normal school life when she meets the most popular boy in school and accidentally nips his neck?

During the summer when everything seemed gloomy I met Sensei and he changed my view on things. The only good trait that Azami, the bashful girl has is that she is honest and diligent. The reason why she kissed him and told him not to forget about her was because she wanted to change herself. During the new school term, the two of them meet again. This time it is at school as student and teacher...

Taken from the Holy Scriptures of the Old Church of Selakiel:
"When the Earth begins to perish, the Messiah will descend from the Heaven on wings of light. Clad in darkness, he will be so little yet he will be so immense surely he shall bring salvation to everyone."

"The four saints shall appear to offer him their assistance. One will give the Messiah courage, one will give the Messiah light, one will give him wings, and one will shield him from his enemies."

Note: Chapters are numbered differently starting on volume 7, since it's a beginning of a new arc

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!

From Aerandria Scans:
Our protagonist, Hikaru, is a member of the astronomy club at her school. On one beautiful starry night, she encounters a tall boy with blonde hair that looks almost white. However, he turns out to be...?!

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.

A cat went in the hot-tempered KANG Jae-Young's villa.
Forbid approach to my room and my library.
Things must be always in place.
I hate messy things and clamor.
Just follow the rules!
Darn! >v<
I won't be daunted.
It's not like that I want to live passively and say no other words but "meow meow".
Seems to be acting modestly, and all of a sudden extrudes the claws while sounding "Grr.." like a wild cat.
Kya~!
Now can love be formed?!!
Let's wait and see.
The vicissitudinous cohabitation diary~

From DGT:
Yating was working in a recording company until she was fired by her boss (a famous movie actress with a spoiled temperament). Discouraged and jobless, Yating decided to work in a pub where a famous group called "Gangster" regularly played. Along the way, she gets to meet this guy who has the most divine voice. Yating's luck then began to change when her uncle decides to retire and set up his own record company. He asks her to join in his ambition to create the most famous rock group in Taiwan. This is the story of how Yating, being the new manager, tried to create the ultimate rock band!

Sakura is the princess of Clow - and possessor of a mysterious, misunderstood power that promises to change the world. Syaoran is her childhood friend and leader of the archaeological dig that took his father's life. They reside in an alternate reality where whatever you least expect can happen - and does. When Sakura ventures to the dig site to declare her love for Syaoran, a puzzling symbol is uncovered - which triggers a remarkable quest. Now Syaoran embarks upon a desperate journey through other worlds - all in the name of saving Sakura.

Riding high on the memory of a boy named Hikaru with whom she spent a day during her last year of grade school, Megu went through middle school without romance. Now that she's a high school student, she has decided she is finally completely over her first love and can look towards the future. But! Megu meets a pretty girl on her first day of high school who gives her a big hug, and her name is Hikaru?!

Note: this manga is currently on hiatus due to its author's copyright infringement. There has been no notice since June 2012 about its re-appearance.

Kohitsuji Project is about a boy being accepted into a prestigious school not knowing he is the "sheep" that is meant to let the vampires learn that humans are not to be treated like food!

(Side stories from both volumes are not scanlated.)

From CoyoMoose:

Lose a game of jan-ken-pon* and you have to confess to the person you love?! From that game on starts the pain, smiles, and tears of confession in this omnibus series!

*Jan-Ken-Pon is the Japanese name for Rock-Paper-Scissors.

Reiroukan is a beautiful house that is currently renting rooms to male and female students. Shirai Genta has just moved to Reiroukan, turning over a new leaf in his life. The house is full of other people with strong personalities, such as the nerdy Tokimaru and the careless and uninhibited Mikoto, who frustrates her friend Midori with her messiness. Genta gets embroiled in all sorts of wacky situations. Soon, though, Genta finds that Reiroukan is scheduled to be closed in a year. At least, there is still a year for Genta to build fond memories with the lively inhabitants of the house!

What happens when two semes want to take control: Takiyama sensei specialized in surgery, seme number #1 wants nothing more than than to seduce and devour Sakuma sensei specialized in pediatry, but there is only one problem, the latter is also a seme!!!!
The story of a seme vs a seme, and about who is going to be on top.

From Pink Everlasting Dream Scanlations:

Sakura Aki is a penniless high schooler who likes to cook and does other "unmanly" things. His grandfather and father are disciplinary on gender roles and beat up Aki everytime he does a thing that women would usually do, like cleaning. When his father leaves him absolutely broke, and with his grandfather realizing Aki's "unmanly" flaws, he sends him to live at one of the dorms at an all girls' school that he runs, a school where distinguished young ladies of the country attend, the Hanayashiki - Flower Estate-, to teach him a lesson.

He meets Kitahiro Renge, a girl with un-ladylike manners and a meat loving obsession. An encounter that's going to save Aki Sakura or just another problem in sight?!

In the near future, the National Police Agency establishes an elite covert paramilitary division called Minkei or Private Police in English to tackle violent criminals and gangs. Among its operatives include average school student Kou Shirashi and school idol Mikuru Nazume.

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!?

From Fantasyshrine:

The Instructor Demands ABSOLUTE obedience!!
A forceful love between an army officer and his student!?

During WWII in Japan, Yamato came to the Imperial Army Academy with the dream of becoming an officer! However, during his entrance exam, an elite instructor named Onizuka pushed him down—!!

The super scandalous love between an egotistic instructor and a prideful top student on campus!!