From Nagareboshi Manga:

Yui has a deep love for her "older brother" (they're not actually siblings, but are related), and she is devastated when he gets married. While at the wedding, Yui meets a sobbing boy, Kaoru. It turns out that his cousin (that he was in love with) is the one Yui's brother is marrying.

When Yui moves into a boy's dorm so she can seek out new love, she finds that the head of the dorm is none other than Kaoru!

From Intercross and Divine Sanctuary:

1) Animal Jungle
Her mother has decided to remarry. Sumi suddenly has to live with three handsome brothers, Amane, Midori, and Hitomi. She wanted to have a happy family, but the house has become a dangerous animal zone. Fighting dangerous situations everyday…?!

2) Saikyou Venus
Aoi is a weak girl... A REALLY, REALLY weak girl. One day, on the roof, she was about to be "attacked" by some perverted guys until suddenly, the strongest and most feared guy in the school (Tatsumi) comes crashing in... covered in the blood of the two half-dead guys in his hands!! The boys run away, leaving Aoi behind... and she faints. The next day, there's rumours going around that... Aoi is Tatsumi's girlfriend!?

3) Ultimate Bishie Paradise
Sachika has always found Mitsuki-kun to be an unbelievably perfect, ultimate bishie. Thus since because of this perfection she finds herself victimized every day which in turn makes her declare to Mitsuki that she will reveal his true colors!!!

4) Oshaberi na Sympathy
After Asahino bumps into Kira they can hear each others thoughts. How can they change this back?

From ShoujoMagic:
Merumo has come to the human world from the Magic Village, and is an extremely pure hearted witch by nature. Her mission is to find a "Bii Men" ("Bee-autiful Face") gentleman... and make a baby with him?! Flying through the air on spinning wings, Merumo searches a school in the center of Megalopolis and causes an uproar. Amongst the gathered crowd, however, are four Bii Men! And so begins Merumo's life as a student...!!

Yousuke and his sister were orphaned at a young age. Yousuke's sister was adopted ten years before the start of the story, since then, he has been looking for her.

One day Yousuke found the couple that adopted his sister, the problem is that they have two daughters, Ayu and Mayu, both of which were adopted from the same orphanage and are roughly the same age. Both Ayu and Mayu had an older brother before being adopted.

Things get more complicated when Yousuke learns that the orphanage where he previously lived was burned down a year earlier, destroying all the records, and that the couple's own records have disappeared. Yousuke must figure out which one of the girls is in fact his sister.

Yoichi Karasuma has spent all of his life in the mountains, training in the Soaring Wind, Divine Wind swordsmanship style. Under his father's guidance, he is able to master the technique at the age of 17. With nothing left to learn, Yoichi is sent to a new dojo located in the city so he can continue to train and gain an understanding of modern society.

Unfortunately, Yoichi has no idea how to act or speak to anyone in the present day and acts like a samurai, complete with odd speech and traditional clothing. As he goes to live with the Ikaruga sisters Ayame, Kagome, and Chihaya, at the dojo, Yoichi, clueless on how to interact with others, is constantly hurtled in hilarious misunderstandings.

From Shoujo Manga Maniac:
Koyuki's family is poor, so her dream has always been to marry a rich man. What better way to try and achieve that dream than to put on a sexy maid outfit and take on a job as a maid in a mansion? Unfortunately, the master of the house is a spoiled brat!

From ShoujoMagic:

For heroine Ooba Kanoko, life isn't much fun. Her family runs a small restaurant, where she slaves and is horribly mistreated by her two sisters, parents, and grandfather. (Not to mention the fact that her name said aloud as "Oobaka no ko" = "stupid kid"!) Poor Kanoko cooks, cleans, and takes the blame when things go wrong. However, her life takes an unusual turn when her family suddenly loses what little money they had, and everything they own is about to be repossessed -- along comes a ragged looking, tall stranger with an interesting proposition that will turn Kanoko into a billion dollar Cinderella! At a price to Kanoko...

Hiromi can't wait for her cousin Makoto to come live with her - but when "he" finally shows up, she gets a good deal more than she bargained for. Toshiki Yui turns a hentai fetish into the plot hook of this high school situation comedy.

From Esthétique:
Boy-crazy Jae Yoo is willing to go through any underhanded means if it means living in the boarding house full of hot guys… Even if it’s going out on a blind date with the dorkiest boy in the school. When she dumps the guy immediately after, she pisses off his handsome best friend Ji Hu and from that point on, the two are constantly going at each other’s throats like cats and dogs. When Jae Yoo finally accomplishes her dream of entering the “boarding house of hunks,” she thinks that nothing could go wrong. An amazing house, a kind landlady, and even a cute guy who seems to be interested in her… What’s this?! Ji Hu is the landlady’s son?! And how is it that he knows about Jae Yoo’s most embarrassing moment in life? What kind of life will the two lead under the same roof? Will they be able to live together at all?!

From Intercross:

1. Bokura no Himitsu o Kyouyuu Shiyou ka
Yuka goes to Ikimonogakari's room to ask them to solve her love problem, but unfortunately, they couldn't help her. To make her feel better, the people in the club gives her a piece of candy. Yuka eats it, and she suddenly gets cat ears and a tail! What happened to her? Will she ever go back to normal?

[T/N: Ikimonogakari literally means "(person) in charge of living beings"]

2. Colorful Shounen to Monochrome na Atashi
Naoki and Kiyo have known each other for a long time because they live in the same apartment complex. One Valentine's Day, Kiyo gave Naoki a chocolate cake, but Naoki threw it away and laughed it off. Because of that, Kiyo doesn't make sweets anymore! Because Naoki's dad is Kiyo's dad's boss and they are going on a trip, Kiyo has to make food for Naoki. Will Kiyo re-live the trauma of the past?
(Also included in the Sweets Fortune Telling Anthology as Boy of Macaroon story)

3. Kaibutsu-kun ni Rei
At the Christmas training camp, Yuzuki was paired up with no other than... that guy?!

4. Itoshi no Himeko-chan
Anri, who is usually bad at handling boys, is asked out by the school's most attractive guy, Takuma! This is so she can gradually get used to guys, however, does Takuma have another agenda in play? What is going to happen between the two?

5) Shiro no Kiseki

Tomoki, a young man with a thing for ecchi stuff, is used to living alone, with his dad traveling all the time. However, he is not prepared for the sudden arrival of his 9-year-old twin sisters, whom he never knew even existed! Toujou Minaho, the big-breasted girl next door, is ready to help out, but these cute little girls are quite a handful.... From Baka-Updates: Kamishiro Tomoki is an Otaku who is studying for college. One day, he received an outrageous "package" from his father: 9 year old blond girls who are his dad's illegitimate children from one of his business trips...... The twins, Selly and Riru are completely spoiled and drives Tomoki crazy. Not only that, the sisters have a "secret" plan to kick out Tomoki and claim the house just for themselves. Will Tomoki manage to make peace with the girls? Read and find out!

Tough, lazy, money lover, yet beautiful high school student named Shin Bia. While she's thinking about the eras she suddenly falls into that ancient time period! She had to transform into an elegant lady and while she's there she faces quite an obstacle.

Yuuki Ashikaga is a high-school freshman at Sakakino Academy. While working as a student librarian, he grows enamored of Kotonoha Katsura, a girl who frequents the library. Unfortunately, Kotonoha is already dating Makoto Itou, another schoolmate.

The situation is further complicated when Chie, Yuuki's older sister introduces him to Roka Kitsuregawa, her kouhai in the basketball club. Roka becomes interested in Yuuki, who only has eyes for Kotonoha. In order to make him jealous, Roka lies and claims she already has a boyfriend, her former classmate Makoto Itou. Unfortunately for all of them, Roka's lie sets off a chain of events no one could have predicted...

Note: Cross Days takes place in the middle of the original School Days storyline and provides an alternate take on how things might have turned out.

Tsuchie Takeshi has dreams of when he played with Hikari-chan as a child. He remembers her as a kind, sweet girl. However, one day on the way home from school, Takeshi is abducted and taken to a huge house, only to find out that she's become an arrogant, violent dominatrix (emphasis on violent). Furthermore, she says that he promised to marry her! How will he adjust to her new personality, and living with her as a new son of her prestigious family?

To cure his persistent virginity, Yuuto Mutsura joins his friend Naota in a trip to Aqua Eden, the "City-by-the-Sea", where brothels are allowed. Before he has a chance to become man, he is separated from his friend and accidentally turned into a vampire! Now forbidden to leave the city and forced to participate in a Public Morals task force with several beauties, how will Yuuto handle this new life?

Onizaki Teppei is a high-school freshman who just wants to live a plain student life, but his world is rudely shaken by a mysterious girl, Mitogawa Enma, who declares her intent to find a husband at the school!

From ryColaa:
Our hero, who doesn't know how to swim, joins his school swimming club and begins to learn from their star swimmer who loves swimming more than anything. Good thing she's cute and nice to boot!

Fortune Arterial's story revolves around the male protagonist Kohei Hasekura, who transfers into a prestigious public school--an English style six-year school, serving junior high and high school students. The school, named Shuchikan Academy, is on an island, Tamatsu Island, off-shore from mainland Japan, and the only way to get there is by boat. This is a series of characters' introductions to prelude the main story.

Kohei Hasekura is a sophomore who transfers into a prestigious public school--an English style six-year school, serving junior high and high school students. The school, named Shuchikan Academy, is on an island, Tamatsu Island, off-shore from mainland Japan, and the only way to get there is by boat. But under the peaceful surface, this prestigious academy holds a dark secret. Some of its students are vampires! And Kouhei will be dragged deeper and deeper into the mystery of the school and the girls that attend.

From Tokyopop:
Aliens have landed on Earth and are now a normal part of society. These beautiful beings have been given the name "DearS" and are trusted and welcomed by most humans. In order for the "DearS" to learn Earth's customs, they are sent to random high schools to "home-stay." When Takeya helps a DearS in his school, she calls him "Master." Thus begins the humorous life of Takeya and his sexy alien follower, Ren, who tries to figure out the wacky customs of this place called Earth!