The Original King (known as the Shinou Heika in Japanese) is the first King of Shin Makoku. His soul watches over the lands of Shin Makoku, and priestess such as Ulrike and Ondine can communicate with him in a limited fashion, one they call "hearing His Majesty's voice." Murata also appears to be able to communicate with him, and is often seen scolding him for meddling in Shin Makoku's affairs.

4000 years ago, the Original King sealed the Soushu into four boxes, which became known as the "Four Forbidden Boxes"; however, while part of the Soushu was sealed in the boxes, a small part of the Soushu infected the Original King to the extent where his right arm seemed slightly decayed. The Original King knew that the Soushu would eventually take over his mind and body completely, so the Original King came up with a plan along with his Great Sage to completely eradicate the Soushu in the future. This involved sealing the Soushu with a pure soul, and destroying it. This soul turned out to be the Original King, but Yuri manages to eradicate the Soushu without harming the Original King, earning Yuri the title of the greatest Maoh. The Original King commented that he was glad he chose Yuri as the Maoh.

The Original King appears to be well alive in the OVAs, having seem to regain a physical body unlike his soul form at the end of Season 2.

Original King told Yuri that with Soushu destroyed, his aim of choosing Yuri as the Maoh has been reached, and Yuri no longer needed to be the Maoh. Since Yuri can achieve his goal very well, the Original King said that he will not hold back the decision of choosing Yuri as the Maoh and blesses him. The Original King has stated he will reduce anyone who opposes Yuri as the Maoh to ash.

(Source: Wikipedia)