wahmbulance SPOILER ALERT wahmbulance
Highlight all that below if you want to really find out about a good deal of Nii's past!!!
...Ni actually was a biologist at a very young age and had his PhD before he ever entered the priesthood. At that time his name was Ken'yuu. When he heard about how difficult it was to become a Sanzo, he decided that he was up for the challenge. Everything else had come so easy to him and he really wanted a challenge.
Well, the time for the holder of the Muten Sutra to die was coming close. Koumyou Sanzo (with his really long hair in a ponytail at the time) came at the other Sanzo's request. The Muten Sutra's bearer held the trials for the sucessor and deliberately didn't invite Ken'yuu. In fact, Ken'yuu had been put in a detention cell for having caused problems the day before. Koumyou had spoken to Ken'yuu and had realized that all Ken'yuu wanted was to be devoured... to be destroyed.
The other Sanzo knew that Ken'yuu would come to the trials whether or not he wished it. And he was right. The other contestants for the sutra tried to stop the soon to be Ukoku Sanzo from killing their master. Unfortunately, Ken'yuu had phenomenal concentration that he didn't even have to chant any sort of sutras in order to kill all of the contestants. When they had fallen, Ken'yuu killed the holder of the Muten Sutra. He stood there covered in the blood of the dead with a sad, dead smile on his face.
He had wanted to die.
And Koumyou had seen everything and gave him the name Ukoku Sanzo...
But the chakra, the denotation of being close to a god, never appeared on the new Sanzo's brow...And that's Ken'yuu's story... Ukoku's story... At least a part of it. This all came from the third or fourth volume of Saiyuki Reload.