While attending Fukuoka University, Nagaishi was signed as a special designated player by Sagan Tosu.
[1] He did not make any league appearances during his time, but was named on the bench once against Shonan Bellmare.
[5] Nagaishi made his league debut against Kataller Toyama on 21 March 2018.
[7] He did not make any league appearances during his time, but was named on the bench once against Fagiano Okayama.
[10] On 17 December 2021, Nagaishi was announced at Avispa Fukuoka on a permanent transfer.