Joker is the main protagonist of the series, stealing precious artifacts as he pleases. He's immensely passionate about his job as a phantom thief, and goes as far as to get noticeably offended and verbal at the accusation of being called a simple and petty thief. He believes himself to be a miracle maker which hands out advance notices, giving fair ground and footing between the victim and himself. Joker believes this is very different from thieves who commonly resort to the tactic of sneaking and going about their business unnoticed in a cowardly fashion.
Joker is seen to have a teasing and mischievous behavior to some things; taunting opponents with humorous yet somewhat rude comments, borderline bullying, and even making side comments about deeds that most certainly would not side with heroic tendencies. Despite such, he very rarely goes through with what's within his words of teasing, as it seems to just be a way to fluster and anger his unfortunate victim.