Wolf Guy - THE ORIGIN

Akira Inugami, a new transfer student to the private school, Hakutoku Gakuen, is actually a werewolf with immortal power when the full moon approaches. The intelligence organizations of various countries attack him one after another.

(Source: Wikipedia, translated)

Notes:
- This two-volume series is the prototypes for the "'Wolf Guy Series" of novels, especially for the first two novels volumes entitled Ookami no Monshou (狼の紋章) and Ookami no Enka (狼の怨歌).
- The series has also been re-adapted with a more violent and mature setting in 2007 by Yoshiaki Tabata and Yuuki Yugo. This new adaptation is known as Wolf Guy - Ookami no Monshou.