From Operation Boredom:

High school Student Kinugawa Kenichi is one of the members of the class committee and also the boyfriend of the super cute Ooumi Chiyako. However, one day, a new student, Kuwabatake Aya, transfers to their school, and demands that Kenichi be her boyfriend...?! Who exactly is this girl, and how does she know Kenichi?

Sidestory of Seitokai no Ichizon.

Hekiyou Private Academy's student council members are decided through what basically is a popularity contest. Since good looking girls are admired by both sexes, unlike boys, the student council room became known as paradise. As the pillar of the student council, Sugisaki Ken seeks to create his own bishoujo harem due to his love of girls.

Haruhiko can't stand his tyrannical father, so he leaves home. The life of a super-rich high school student is difficult. By relying on his relatives, he ended up with a large debt... Even with his classmate Yoriko and his maid Nanako helping him out, things just keep happening in his unfamiliar economic lifestyle. It's a promise-filled, high tension, romantic comedy!

Mina, a Lieutenant of the Space-Time Vanguard Unit arrives from the distant future to interrupt Ichikawa's peaceful life with some upsetting news of how the world would end-up if he continues to pursue his affection about his little sister. The sound of the grim news doesn't seem though to deter Ichikawa resulting in Mina having to take any and every possible action to convince and if necessary seduce him!

Souma Kenichi is in a bit of a pickle. A group of thugs has cornered him on the side of the road and seem very intent on his life. Desperately fighting them off with the longsword he can summon at will, he is saved when a famous teacher of the Miyazaki School and his student intervene on Souma's behalf.Confused but grateful, Souma learns that the sword he wields is called a "shinbuki", or true weapon. Stronger than any steel blade, a shinbuki is created by channeling inner energy into your surroundings and materializing it into a weapon. Normally, learning to wield these supernatural weapons takes years of training under a master. However, a coveted few like Souma are born with the ability to wield shinbuki at birth, and master its use at a startling rate. These rare prodigies are called "Tensaiji".Hunted by a mysterious organization intent on eliminating him before he can become a threat, Souma has little choice but to accept his benefactor's offer of free admission into the Miyazaki School.Note : This manga read from Left to Right

Himoto Sora is a transfer student with a sense of justice and dreams of becoming a knight. Upon arriving at Utopia Gakuen, she learns of a virtual reality-like game played by the male students in which they use girls as weapons in battles for status and treat them as commodities. Seeing one of these girls being abused she steps in and through some sort of error unwittingly becomes the first female participant of the game.

Republished in 2017 in a 3 volume omnibus
1) Shitsurakuen - Hangyaku no Otome no Shou
2) Shitsurakuen - Shinai no Otome no Shou
3) Shitsurakuen - Rakuen no Otome no Shou

This manga tells a story about new Demon Lord Vellmort XIII. Day after day he suffers from boredom, because all Underworld is already conquered by his predecessors, nobody (except maid Sarah) dares to oppose him and he is already sick of luxury food and jollifications with concubines. But some fateful day he has found a solution and together with Sarah has gone to conquer the Ground, populated by humans. Will he succeed in his plan or will he die by the hands of justice? 

Aliens exist for sure. Even a child knows it. The world is protected by a group of aliens with special power. Daichi lives in such a world. He terribly got burned five years ago, but it's all cured and he now lives a peaceful life. But one day, he meets one of the aliens and his life slightly changes...

He is forcibly appointed as to be an examiner of the next protector test. There are also three girls who move to his school to take the test and one of them is his childhood friend. He still doesn't know that there will be a big event, which will change his future, in the not too distant future...

[From ErogeShop]

From Spoils:

A School Pop Comedy!

Masaki Aoi is a high school student with a sweet tooth. All her life she has been treated like a boy but change is on the horizon for this tomboy! Yuase Takumi is a third year middle school student. He's also the president of the Confectionery Club, and he's extended an exclusive invite to Aoi to join his club....too bad he thinks she's a HE! But pressure from her classmates forces Aoi to play along and she finds herself joining the Boys-Only Confectionery Club.

What will await her?

The taste of hands make them addicted.. and ruin their life.

"Sensei! This is different from the school life I expected!"

Mizushoubai (water business) is the term for Japan's night life activities, such as fuuzoku (similar to prostitution but none of the illegal bits), hosting and managing (entertaining at bars), and kyabakura (night clubs). Recently, it was decided that a high school should be founded to educate the youth in these areas where they previously had no such guidance: the School of Water Business, "Mizushou", located in Tokyo's Shinjuku ward.
The story is from the perspective of a teacher, Tanabe Keisuke, who was transferred there to help teach that school's first generation of students.

If you do as I say, I will let you taste heaven~ An exciting story of living in a women’s only house along with five girls who all have different fetishes~

From Rayns&Lele Scans:

For the second son Takeda Yoh, love is to be able to choose "the one" who stands above all others, to choose the her who is the most precious to him, and the her who he wants to protect the most. He found love in Tsubame, an adopted sister, and everything was fine...
...until his two brothers confessed their feelings to Tsubame. It's time for her to make her choice. Who will be her precious "one"?

"The only person who I can give happiness to... The only person who I like is..."

"I am Kikyou! I'm working part-time in this cute little flower shop called "Tsumikabatsu". My boss, Baramon-san, is extremely popular with girls and he's a master at flower arrangements! He's a well-respected person. But, WHY does he have to stand so close to me... Aah, Boss, wait! Stop that!" I'm trying to introduce the story here, DON'T TAKE OFF MY PANTS!!!........So, so it's like that, please read this "the beautiful boy working hard in the flower shop, "Tsumikabatsu"!

Princess of romance, Hwi-Kyung. The handsome, wolf-like, Three Musketeer guys who run to Hwi-Kyung wherever she is.
They make a secret promise without Hwi-Kyung knowing. If one of them starts to love Hwi-Kyung, their friendship will shatter.
A no-love oath.
The prince of confidence, Yoon Suh-Rin's, charm!
Te-Ri, who became a two-timer because he loved Hwi-Kyung!
And the one who hid his love for Hwi-Kyung's happiness, the charismatic Jo Hwan-Sung's sad love story!

Based on a popular otome game, Hakuouki follows Chizuru and the Shinsengumi in an alternate reality. Chizuru travels to Kyoto in search of her missing father but after being involved in an incident, ended up being taken in by the Shinsengumi where she meets the members including the famous Hijikata Toshizo and Okita Soshi. Chizuru’s father was conducting government research for strengthening the Shinsengumi and developed the ochimizu. The ochimizu is a formula that gives demon like strength and regeneration effects but once taken, the user experiences extreme pain and eventually turns into a blood hungry monster. In an attempt to defend Chizuru, Hijikata takes the ochimizu and although the situation was saved, he is now affected with the illness. Okita is also forced to take the formula when his tuberculosis prevents him from defending Chizuru and himself. Feeling responsible for their actions, Chizuru must fight her feeling of helplessness and find the courage to support the Shinsengumi.

In a universe where men and women are mortal enemies, Hibiki is captured by a band of female pirates. The group find themselves stranded with a super ship they dub the Nirvana and set out for the female home planet. Along the way, they discover the existence of the "The Harvest" and the possible destruction of both men and women.

The manga differs greatly from the anime, with fewer characters and focusing more on the relationship between Dita and Hibiki.