Muki was the son of Toyo Nobi, a key military advisor and the close personal friend of shogun Matasuuri Nagahide's father. However, when Muki was 11, his whole family, including his father, were killed by bandits. That night, he silently entered the bandits' camp and killed all them in their sleep. All this was observed by a tengu tribe that was impressed by the young Muki that they invited him to their village. Muki remained with the tengu for two years, learning much about military warfare and guerrilla tactics. Afterward, he went back to civilization and soon Nagahide appointed him as daimyo of Chozawa and one of the Three House daimyos.
Muki was a soldier at heart, always waiting for the next time to led his men in a battle. He was also brutal and unforgiving, adorning his land with the impaled decapitated heads of state enemies.