Arth (also translate to Earth) is a Mamodo who appears like a living armor and descended from a long line of peacekeepers. He hopes that when he becomes the Mamodo King, he can write up laws that will bring about peace and stability.

Arth's ability is swords. Also, the sword Arth used can absorb other Mamodo energy when they get hit or touched.

He initially encounters his partner Ellie living in a Finnish hospital. Arth and Ellie's relationship is notably similar to that between a master and servant (at Arth's request). Arth is shown to be extremely soft when concerning his partner.

(Source: Zatch Bell! Wiki, edited)