After that, Nagashige worked for the bakufu (the samurai government) as a second son of a fudai-daimyo and was appointed as chuoku-kosho (a servant in the semi-deep portion of the castle) on August 26, 1670 and, on February 7th, was supplied with 500 pyo (originally, hyo, a unit of rice amount equivalent to 60 kg/hyo) of kirimai (seasonally supplied special salary rice).
以降譜代大名の次男坊として幕府に出仕し、寛文10年(1670年)7月11日中奥小姓に就任し、12月28日には切米500俵を支給された。