English name: Crown Prince of Darkness
Label: B's Log Bunko
Publisher: Enterbrain
Author: Kanazawa Ariko
Illustrator: Itou Akito
Volume: About 16 Main and 4 Gaiden
Summary: (From the back of the 1st volume manga) "I will kill you, Nii-san," said Kotoi, Ko's younger-brother-from-a-different-mother who one day suddenly appeared in front of him. With the struggle for the throne of the world of darkness as the reason, Kotoi was aiming for Ko's life. On the other hand was Abe no Seimei, an Onmyoji from the world of darkness. Ko's life was suddenly thrown into chaos by the appearance of these two and the fact that most people around him were in reality a part of the fight for the throne...
(From the Official Website) Ko, who was just a normal high school student, was suddenly chosen as the successor of the King of Darkness. Surrounded by a sharp-tongued brocon younger brother, the weirdo onmyoji Abe no Seimei, and a bunch of husband-love Shikigami, the training to become the next King of Darkness begins...?! The Onmyoji Battle Comedy full of handsome men unfolds.
Yeah, sorry about really horrible summary. I can't read Kanji at all (which makes translating that tiny bit from the website really hard) but I can understand the spoken language adequately. Which means I can smoothen out whatever Google Translate churn out by reading the latinized words below the box. But I'm nowhere the level to translate this myself.
I fell in love with this series after reading the manga, of which 2 volumes were published in my country. It was pretty funny and interesting. The overall feel was quite like what would happened if Kyou Kara Maou was set in a Medieval Japanese world instead of Medieval Europe. Dunno if anybody would be interested, but it would be lovely if somebody picked this up.