After he was adopted by his older brother Takakane FUKASE, he was asked to take care of Iwaya-jo and Fukase-jo castles, but Ietoshi devoted himself to being yamabushi and spent a whole day practicing, and used to live in Bicchu Province for a period of time.
兄の深瀬隆兼の養子となり、祝屋城と深瀬城を預かったが、家俊は山伏に身をやつして修行に明け暮れ、一時期備中国にも居住している。