Enma Daioh

Enma Daioh (閻魔大王), also known as Taizan Fukun (泰山府君), is a fictional character in the Shaman King manga and anime series. An underworld god worshipped in East Asia, he is a ruler of Hell and was tasked with guarding the Spirit of Earth.

About
As a gigantic being, Enma wears traditional Japanese robes, has a big beard and wears a crown with the kanji "王", which means "king", on it.

Using an onmyōdō technique, Asakura Hao created a contract with Enma in order to control his own soul and reincarnation after death.

After the reincarnated Hao stole the Spirit of Fire, the Patch Tribe entrusted the remaining four Grand Elemental Spirits to four rulers within Hell, with Enma guarding the Spirit of Earth.

During the Shaman Fight in AD 2000, Sati Saigan entered Hell and confronted Enma in order to retrieve the Spirit of Earth for the Five Elemental Warriors. Although Enma and Sati had known each other for a long time, Enma was bound by the contract with the Patch Tribe and refused Sati's request to turn over the Spirit of Earth, so she had no choice but to fight the king. She ultimately succeeded in defeating Enma and securing the elemental spirit.

Anime/Manga Difference
While he is mentioned, Enma does not appear in person in the 2001 anime series.