He is keeper of the Tenchi Kaigen “Muten” Sutra, and one of the active Sanzo priests. Currently he hides his origins, and shoulders the role of executing the Gyuumaoh revival experiment at Houtou Castle, although his purpose in doing so is unknown. He is always observing the movements of the Sanzo Ikkou from afar. He encourages trouble from afar because he enjoys watching their future like a game. This isn’t limited to the Sanzo Ikkou; he has the nearby Kougaiji group at his mercy with his belittling behavior.

He was born and raised in an extremely normal, albeit rich family. Both his parents were graduate school professors. Although he entered graduate school at a young age, skipped a few years and received his doctorate in accordance with his parents’ expectations, one day he suddenly left home to become a Buddhist monk. He had an interest in the Sanzo priests, and had become an apprentice monk called “Kenyuu” when he met Koumyou Sanzo. After murdering the previous Sanzo priest Goudai and succeeding to the title of Sanzo priest himself, he was christened “Ukoku” by Koumyou. He wandered the world with Koumyou for a year, after which he set out on a solitary, roaming journey.

Nii Jienyi is another face of Ukoku Sanzo, a temporary guise known as the “leading professor in life sciences”. He effaces the dignity of a “Sanzo priest” by spiking his hair, growing stubble, and wearing a shabby white coat. Because of his outstanding skills in science and knowledge of youkai magics, he is the only human allowed to live in Houtou Castle. He has a physical relationship with Gyokumen Koushu. Although he usually puts on an act of flattering her, it seems he is skillfully pulling the strings behind her back. Recently, he pulled the “Muten Sutra” from within the stuffed bunny he had always carried around with him, and once more begins to act from the shadows and “Priest Ukoku Sanzo”.

His power is to bury all creation in a darkness blacker than night. It voids any and all attacks.