Nagayasu worked on the reconstruction of the embankment of Kamanashi-gawa and Fuefuki-gawa Rivers and the development of new rice fields as well as the mining of gold in Kai Province, and reestablished the internal government of Kai Province within just a few years.
長安は釜無川や笛吹川の堤防復旧や新田開発、甲斐の金山採掘などに尽力し、わずか数年で甲斐の内政を再建したと言われている。