Nishiguchi was part of Chukyo University school team where he participated in the 2018 Emperor's Cup. On 26 May2018, he helped his team overcome a 2–0 deficit in extra time by scoring the first goal where his team eventually made the comeback by winning the match 3–2 against Saurcos Fukui thus qualifying to the second round, Nishiguchi also played in the next match against J1 LeagueJúbilo Iwata but was bowed out from the tournament after suffering a 3–2 defeat in extra time.
On 14 December 2020, Tanjong Pagar United announced the signing of the Japanese forward for the 2021 Singapore Premier League season. Reo started all 21 games for the Jaguars in the 2021 season and amassed a return of nine goals and four assists in the season. Reo bettered his form in the 2022 season, scoring 30 goals in 30 games as he finished third in the goalscorers' chart where he also scored his first career hat-trick which ended up scoring 5 goals and assisted one in the demolishing match against Young Lions in a 8–1 win on 1 October 2022.