Zagine Axelox was a skilled assaassin who trained Train Heartnet after killing his parents.
Zagine Axelox is the man who killed Train's parents. Not knowing that they had a child, he let Train live and trained him in marksmanship and other killing techniques. He also gave Train milk to drink, telling him that it would make him strong, which might be the reason Train always drinks milk. He always pushed Train to be "the best" so that Train could finally get revenge on his parents' deaths.
One rainy day, Train returns from buying groceries to find Zagine bleeding. Train tells him that killing Zagine was his goal. Zagine then tells Train to live and become better than he ever was. Zagine dies moments later.
In the Anime, an image of Zagine (which is only an illusion, and not the real Zagine) appears and attacks Train while he is trying to destroy Eden. Train manages to beat his old teacher and destroys Eden.
Marksmanship: Zagine is a highly skilled marksman, able to tear a target sheet from the inside out.