Leonard is an ancient being, who long ago made a pact that took his ability to age. He is a kind-hearted boy, who often seems to have a crush on Lucia, and completely idolizes Mitsunari. He cannot wield weapons, and doesn't know how to fight, but he is a very skilled wizard.
Leonard is a very dangerous person, even though he cannot fight, due to the fact that his pact-partner is a thousand foot tall Golem, which would slaughter anyone who dared to try and hurt the child.