In the 30th century A.D., in a world in which magic exists, 100 years have passed since the human race won a war against the Devil King. Even though the war caused many sacrifices, slowly but surely civilizations began to rise again.
One day, a virtuous child named Sai Akuto ("Worst Evil") is adopted from the orphanage he's lived in ever since a witch quietly left him at the church as a baby.
Five years later, Akuto passes the test to enter Constantin Magic High School. But after arriving and taking the vocational aptitude test, Akuto receives surprising results:
Examination Numbers: Number 021
Name: Sai Akuto
Future Occupation: The Devil King

Loser Yarahata Kanji can't even have a normal conversation with a girl let alone have any kind of relationship with one. But one day a ghost named Aiya appears and declares that he has been tasked with the mission to change Kanji's life. At this rate, the Yarahata name will not live on so Aiya will become a love doctor and coach him on how to develop relationships with girls.

The first hurdle comes when he starts a part time job at a convenience store and sees that his co-worker is a hot girl named Yoshizato Saki who also happens to be the store owner's daughter. With the help of Aiya, Kanji, although stumbling along the way, has a conversation with her and builds a relationship. But he has miles to go if he wants to be the kind of person that can date beautiful women.

School girl is trained by a secret branch of the police to detect and to kill demons disguising themselves as humans.

After 10 years of training, Yoichi returns home to fight against the Wenkamui, an endless horde of mysterious monsters that threaten the safety of his village. He's not alone in his fight; his best friend Ryuu, drawer of the divine sword Kamui, has also spent this time training to fulfill his destiny. However, a decade is a long time, and upon his return, not everything is as Yoichi expected it would be...

[Written by MAL Rewrite]

What would you do if you were given the power to make your own rules in which everyone has to obey to them?

From Easy Going Scans:

In a future devastated by war and desertification... is unexpectedly, a flower shop!

From Tokyopop:

Yume innocently uses her magic to help the people she encounters--soccer players, the wrongly incarcerated, or two young lovers wanting to see the moon on a cloudy night. And you can bet that Yume's magic leads to new adventures--and a few mishaps!

This is a 4-koma comedy about a young girl named Ichimatsu Kohina who got possessed by a low grade spirit called Kokkuri-san.

Nakahara Yukiko stumbles upon a class filled with supernatural students... Just what are these weird misfits doing in a human high school? NOTE: READ FROM RIGHT TO LEFT. ALSO MASSIVE ART-CHANGE AFTER THE FIFTH CHAPTER. 

From Chibi Manga:

After she took some medicines, Michiryuu became suddenly a little girl. People used to say that she was perfect. That's why she wants to go back to normal as quick as possible. But that will only happen if she can find a person she can fall in love with. That's completely impossible for her! So what can Michiryuu do?

From Shoujo Crusade]:

10-year old Niina is special. This is because she has the memories of her past life as a girl named Chitose still intact. Among these memories is a promise with Chitose's boyfriend which Niina then decides to try and fulfill. But can she really?

Includes the following one-shots:
Koi Baka. (volume 1)
Toda is a really smart girl but has no passion for anything. She admires idiots who are passionate, especially her classmate, Iijima.

Machibito (volume 4)
Komako is a carefree girl, who's pretty incoherent. Whe. a random guy asks her to eat sweet potatoes with him, she can't help but wonder why he pats her head and thanks her everytime.

N/A

Jung Yoon-hwan may be an orphan but he was a college student who was focusing hard on his studies, one day he is brought to a mysterious "White room" to fight even when he does not want to. Every time he defeats these monsters he gains psychic power, magic, and items beyond his imaginations....

(Source: Game of Scanlation)

The sky has constellations, and humans have teeth. The earth has hills, and humans have little things.

First year high-school student, Toujo Basara, is now living with two beautiful step-sisters thanks to his eccentric dad. But Mio is actually the new Demon Lord and Maria's her succubus chaimberlain. Throw in a "reversed contract," rival demon tribes, and the ecchi situations mainly brought on by Maria for good measure, and you have a situation where Basara's life will never be the same. This seinen adaptation of the light novel mostly focuses on the said latter ecchi situations that occurs between the three main characters.

N/A

When Masami's father died, he was told by his grandfather that he had to move out. In order to find a new place that he could live in for 80,000 yen a month, he asked his unrequieted love "Kagome" to look for a new place for him. But unfortunately, because of that, he has had to join the "extremely normal phenomena observation society" that she founded. And on top if it, there are rumors that things seem to "appear" at the things that the she finds.

On a rainy day, when Mai got stood up by the guy she likes, she met a beautiful girl who told her that she was the Rain and that she had come because of her tears. After that Mai's days were filled with the bitterness of betrayal, only the memory of the girl called Rain can somehow ease her heart. A story of a brief love affair under the rainy season.