Kurozakuro

Kurozakuro (クロザクロ) is a manga series by Yoshinori Natsume. The series was ended after seven volumes.

Plot
Sakurai Mikito is a high school student and is bullied everyday, but doesn't fight back. This changes when he swallows a mysterious orb. He starts to have the desire to eat humans. In his dreams he talks to a strange boy who is called Zakuro. Apparently the orb he swallowed was an ogre core which transforms a human into an Ogre. When Mikito was discovered by "Ogre Hunters" and the story develops from there.

Manga
In North America, this series has been licensed by Viz Media with the first volume scheduled for November 2010.