From Intercross:
When Yui's parents remarried, she gained 5 hot brothers! Currently she likes the really cool Masaki however she feels insecure. Does he really see her as his girlfriend?

Kamisu Iori is at that age when he really wants a girl, but he's about to get more than he bargained for. Iori is taking a nap in the forest when a cute girl with cat ears and tail falls on him from the trees. She scurries away and he chases her through a mysterious door somewhere in the forest. Iori wakes up in a café where he learns that kittens actually take the form of a human with cat ears and tail just like Keena, the cute girl he was chasing. But when he accidentally breaks the door that he came through, Iori has to work at the café surrounded by “kittens” until it gets fixed and he can go home.

Hino Akiharu lost his parents when he was an elementary student and was taken in by his uncle's family. One day, he sees on the news about the newly-established Hakureiryou Gakuin, a school which was re-built from an elite girls' school. He decides to take the exam for that school and succeeds in entering the House Management Department (the place to train maids & butlers). He wants to become a butler, although his appearance scares the ladies. Akiharu has a sinister look in his eyes, a scar on his right eyebrow, and bristled up hair. Add 3 piercings on his ears and he indeed has a typical bad boy look on him. He meets his "nemesis" at that school, Saikyou Tomomi, a girl with a two faced character who traumatized him many times since they were kids. Another girl named Cernia Iori FlameHeart chases after him because of his looks and calls him suspicious. Still, Akiharu starts finding his feet at the school and his relationships with the girls also get better...

Dimitri Lewandowski is a celebrated tenor in early 1900s Vienna. When he is killed in an accident, his corpse is colonized by the seeds of a vampire master. At first, Dimitri denies that anything has changed, but as the people around him start dying, he is forced to accept the ghastly truth.

Flash-forward to 2008. In Tokyo, Azusa Kikukawa’s troubled love life comes to an end with a fatal accident. Dimitri appears in her dying dreams with a diabolic proposal—he will save her lover if she agrees to become the breeding ground for the next generation of vampire seeds…

When Riki was a kid, his parents passed away. What saved him was a group of his friends who called themselves the Little Busters. They took Riki out and played together with him. He really enjoyed it and his grief gradually faded away. And now, they are in the second year of the same high school. They still hang out together and enjoy their school life....

Around the the 37th year of the Meiji Era (1904) in the midst of the Russo-Japanese war, the small Japanese army, in need of assistance, uses its special flying (thanks to a benevolent demon) ship, the Amanohara, to attack Russia's major base at Port Arthur (Lushun).Umakai Shintaro, a Russian diplomat originally from Japan, defects and goes to Sapporo to teach at a girls academy. However, that girls academy is not typical - it is on board the Amanohara, and the five girls Shintaro teaches are known as the Lime Unit - girls with the ability to summon powerful beings to fight for them.Based on the visual novel of the same name.

A sequel/spinoff of the Alice in the Country of Hearts manga. It’s happy ever after for Julius and Alice who are now lovers. But married life with the morose, antisocial workaholic Clockmaker is not without its problems. Now a “crazy storm” that is said to change everyone it touches is about to arrive. What further adventures are in store for Alice Liddell in this strange Wonderland?

From ShoujoMagic:

After failing the entrance exams to her school of choice, Hiyo Osora gets an acceptance letter from SM Academy. But she didn't even apply or take its exam! When she arrives, there's something amiss -- all the students are... monsters!? And the head of the student council says he's her fiancé right before he sprouts giant black wings! What strange fate brought Osora to SM Academy, and what supernatural fate awaits her after this!?
*Volume 9 contains an extra story called Kitakubu.

Love Rush is about monsters who fall in love with the main character, and they all want to marry him.

Kensuke is your usual high schooler. He's unattractive, unreliable and leads a very boring life. This all changes in one night, when a goddess granted him his wish and makes him a popular boy. And soon after that girls start flocking to him like there is no tomorrow. The first dramatic change in his life came from his sister and the second was a childhood friend that he had no idea existed. Things don't just stop there, soon all sort of weird girls come knocking at his door. These girls ranged from Nekomimi, Magical Shoujo etc. His love drama filled life is about to begin...

Ryou's mom died when he was young, and his dad is always at work. Now with a new girlfriend, how will his life be turned upside-down when he finds out a classmate of his is going to be his new stepmother?

From Tokyopop:
Yuuichi Tate is overjoyed: He gets to go to a brand new high school. Of course, then he just happens to find out the school he choose is under frequent attack by strange creatures called ''Orphans'', and the school set up a special task force of female members called ''HiME''s, using various elements as their powers, to battle these invaders. That's not all, though. Each member of the HiME task force has their own, unique ''Key'', another person whom, upon being discovered, can team up with the HiME to create a ''Child'', a combative unit specifically needed to effectively battle these Orphans. And with Yuuichi's luck, he just happens to find out he's not just the ''Key'' for one of the HiMEs, but for two... Two highly competitive, rival schoolgirls. And that's only the start of the trouble.

Kakusho Bizarre adventures in the world

Marriage Royale's story revolves around the male protagonist, a high school student named Tsukasa Hinomoto, who is told one day by his parents that he was adopted. Furthermore, they tell him that his real father is a manager of a large company, meaning he is very rich and holds a lot of power.

Tsukasa's real father wants his son to marry a good woman, so he sets up an event known as Marriage Royale. Beautiful girls from all over Japan will come together at a school built especially for this event and vie to become Tsukasa's fiancé.

The school is located on an isolated island near Japan, and Tsukasa himself is taken there to live in a mansion in the care of two twin maids: Miku, the elder sister, and Miu, the younger.

From Intercross:

Ouri is a girl who dreams of getting married to someone who will protect her, just like her dad protected her mom. When she refuses an arranged betrothal to someone she doesn't know, her mom insists she attends Clover Academy, where there are plenty of fiancee candidates. Rumors about her quickly spread around the school, causing many boys to swarm around her.

Then, caught in a pinch, she's suddenly rescued by a "Meteorite Guardian" named Knight, who is now contracted to Ouri to protect her...