There is a rumor around school about Houjyou Aika giving birth to a child at the age of fifteen, just now returning to school about a year later. Reality is far worse than the gossip. Aika was raped by the demon ruler (Suruga) and she somehow survived long enough to give birth to a boy. The half-demon was taken to the 'real world' (aka demon world) by his father and imprisoned in the "Cliff of Time". During his time there, Kai was a plaything to his elder brother, Kaiga.

This is a serious series with rather violent, bloody scenes. The demons have no morals, seeing the human world as a big playground and sex with anyone is just fine. The only mistake Kai made in his life was existing, and he is constantly punished for it.

From Reverein Scanlations:

A boy who while walking on the way home sees seven bright dots fall from the sky. He goes out to investigate and finds himself in a strange forest filled with really pretty “fairies” who really like tea. Reminiscent of Alice in Wonderland and Snow White, it’s a cute little story of self-revelation.

In this country, there are beings called Sapeles. These beings are not human; they are treated as slaves. Society shuns them, just as they would poor people. Sapele are not allowed to have desires, especially desires for things like love. If they do, they are considered broken, useless. Lepu Le is a Sapele trying to come to terms with himself, not understanding or knowing anything about who he really is, or where he came from. After a fateful encounter with a broken Sapele known as Roie, he starts to question what he is told even more.

A collection of Dragon Kishidan oneshots and side stories:

One Day, Another Day
Set before the end of the series, it's basically a side story of a day in the Dragon Castle, kind of in Zoma's perspective.

Juuji ni Hikaru Hoshi
Takes place before the events of the actual series. This is a back story that shows how Lykouleon and Raselane met, introducing Lykouleon's uncle, Fieruto.

Mamono no Mori no Kioku
Another backstory that delves a little bit more into the relationship between Bierrez and Cesia before the series started. It also shows how Nadil became the demon lord.

Happiest Children
This actually has three little side stories in it. The first one is about Rune's dream about everyone dressed in drag, the second is about a little adventure that the three dragons go on, and then the third is like a day in the life of Alfeegi, Ri-ma, and Duma.

Crescendo
Backstory about how Lykouleon and Kaistern met and how Kaistern then became the Blue Dragon Officer.

CONFESSION - Thats
This is basically the backstory of Thatz and how he knew about Rath's little secret.

CONFESSION - Rath
Basically telling a lot about Rath, particularly his relationship with Kaister.

From Reverein Scanlations: A series of short stories featuring two characters with the same name, Asuka Koji and Takaki Asuka. They both have super powers and share a common love: SAKE! This really has no real plot but it provides a lot of entertainment and random characters from her other works also appear.

From Tokyopop:

If you think facing a man-eating witch is dangerous, imagine having to face the one-eyed monster that ate it. In a farcical tale of hijinks and swashbuckling adventures, Rath, Rune, and Thatz become the Dragon Knights of Fire, Water, and Earth and scour a mystic landscape.

Their quests? Fortune, love, and honor. And though they may have to work together, no one says they have to like it. The Dragon Knights are put to the ultimate test when their fighting involves more than just their enemies.

The sequel to Dragon Kishidan, set 500 years after the original series.

From Reverein Scanlations:

We all know about school rivalry, but these two schools take it to a whole new level.

From the back of volume one:

The liberal traditions of Aoinomiya Gakuen and the disciplined traditions of Kaburaya Gakuen. Sharing the same territory, to this day these schools continue to compete violently with one another, and the fateful relations of the long-held Jintori Game unfold. If all three jin are stolen, the school itself will cease to exist.

Then one day, Aoinomiya’s new Princess was abducted by Kaburaya.

Akira who pokes his nose into everything, Kaiki who hates ghosts, and Shinobu who is actually a powerful son – the three of them set off to investigate—

Jintori Gassen (Game) is Ohkami’s newest and currently ongoing series. Filled with a number of characters from both Aoinomiya and Kaburaya, there’s plenty of comedy, action, intrigue, and even some romance to be had.

Set in a legendary kingdom, magic user Senri and his friends have been searching for a certain person. According to the instruction of the “crown,” that person is supposed to be in the universe below the palace. However…?! [Reverein Scanlations]