Nishiguchi was part of Chukyo University school team where he participated in the 2018 Emperor's Cup. On 26 May 2018, 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.
Albirex Niigata Singapore
After graduating from Chukyo University, Nishiguchi was eventually recruited by Albirex Niigata (S) for the 2020 Singapore Premier League and started the season perfectly by scoring in 5 straight games.[1] He eventually finished the season with 5 goals and notched 1 assist in 11 league appearances as he helped the White Swans to the 2020 Singapore Premier League title.[2]
Tanjong Pagar United
On 14 December 2020, Tanjong Pagar United announced the signing of the Japanese forward for the 2021 Singapore Premier League season.[2][3] 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.[4] 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.[5]
Gyeongju KHNP
On 23 February 2023, Nishiguchi moved to South Korean to signed with K3 League club Gyeongju KHNP. On 15 April, he scored his first goal for the club in which was the only goal in the match as he won his team the three points in the league against Chuncheon FC.