Stringendo & Accelerando Ultimatum: Sera (2008)

Male student Souta Tsukishima begins working at his family's public bathhouse as a back washer. While concealing her true identity, Souta's classmate Aoi Yuzuki visits the bathhouse. A relationship between the two begins to develop when Souta washes Aoi's back.

Struggling yet brilliant, 19-year-old Minato Sahashi has failed his college entrance exams for the second time, resulting in him being regarded as worthless by those around him. However, the course of his seemingly bleak future is altered dramatically when a beautiful, supernatural woman falls from the sky and into his life. That woman, Musubi, is a "Sekirei," an extraterrestrial with extraordinary abilities. Recognizing the potential of the Ashikabi gene within Minato, Musubi kisses him, initiating a bond between the two of them. This drags him into the high-stakes world of the Sekirei, where he and his new partner must compete against others in a battle for survival called the "Sekirei Plan." However, unbeknownst to the contestants, there is far more at risk that what the competition initially entailed. Manga series by Sakurako Gokurakuin.

The story takes place in Japan in the early 21st century, in an alternate reality where the Tokugawa Shogunate has remained in power. In this reality, student councils are tasked with oppressing schools. Yagyuu Muneakira is a high school student who rebels against his student council with the help of girls who've had the names of famous samurai heroes passed on to them.

This romantic comedy is about Takeru Ohyama, a typical perverted teenage boy. His new school doesn't require entrance exams, and it just turned co-ed! Unfortunately, his dreams of a happy high school life are dashed when he finds out the school is much more than it seems. All of the students wield a special item—a Maken—to unleash their magical abilities in duels! Can Takeru find a Maken that works for him? Even while trying to fit in at a new school and dealing with all kinds of girl problems?

When Mafuyu Oribe and her adopted sister Tomo rescue a strange wounded man, they have no idea what they’re getting involved with or what the consequences will be. Alexander Nikolaevith Hell is an Iron Qwaser, one of many opposing factions of super-warriors.

Shion and Rui are the dream team when it comes to hitting on women. Tonight was going to be another night of hooking up with girls for Shion, but he ended up taking a strange drug. When he woke up... he'd turned into a girl?! Rui came looking for Shion, but didn't recognize him, and started hitting on him...

16-year-old Hayate is really down on his luck. Because his unemployed parents are good-for-nothings who waste what money they have on gambling, Hayate had to start working at a young age to help out his family. Although such experience has made him inhumanly fast and tough and skilled at things boys aren't normally skilled at, it has also left him in an awkward position, as his parents have racked up such a huge gambling debt that they have sold Hayate to the yakuza for the value of his organs. In a desperate attempt to avoid that fate, Hayate decides to become a "bad guy" and kidnap someone to be held for ransom, but his efforts to do so are mistaken as a confession of love by the girl he targets. When he helps save the (as it turns out) ultra-wealthy 13-year-old Nagi from real kidnappers, she takes him in and gives him a job as her new personal butler (and love interest) until he can pay off his debt. But Hayate is more attracted to Nagi's beautiful teenage maid Maria, and head butler Klaus is initially disapproving of a boy with such a poor look. And then there's Nagi's pet Tama, who is also a force to be reckoned with.

This is the story of a boy, who became the lone Adam among four billion Eves. In a world where a pandemic has rendered all men impotent, high school student Itsuki is the exception who escaped it. In order to protect this secret, he transfers to a very special high school, which turns out to be composed of 90% girls! There, he encounters an upbeat and friendly senior, a sexually frustrated female teacher, a tomboyish school 'prince,' and an heiress from a wealthy family. For Itsuki, who has his pick of any woman in the world, the question remains: which one will he choose?

Small for his age, Yukinari has been bullied and abused by girls all his life. Now in high school, he has developed a rare condition: whenever girls touch him, or even come close, he breaks out in hives. Imagine his surprise, when he is suddenly transported to the city of Seiren on a mystic world invisibly orbiting the Earth, and populated with vast numbers of women and very few men. Fortunately, he has a new friend, Miharu-chan, whose touch inexplicably doesn't affect him.

Yamada is the cutest girl in the entire school, and she wants to have her way with 100 different boys before the final bell rings. There’s just one problem: she’s never even been kissed! Lucky for her, class geek Kosuda is ready to serve as her own personal Sex Ed dummy! Can these wannabe lovebirds master the art of seduction before the sun sets on high school forever?