Nagakura began his career with Urawa Reds Junior Youth (under-15) after being scouted from junior high school. Despite being physically smaller than his peers, he was technically skilled and eventually earned promotion to Urawa Reds Youth (under-18).[2] In 2017, he scored 7 goals in 18 appearances in the Prince Takamado JFA U-18 Premier League.[3] Nagakura spent three years with Urawa Reds Youth, but was not offered promotion to the first team, so he decided to go to Juntendo University.[4]
After finishing university and not receiving any offers from J.League clubs, Nagakura decided to join fifth-tier Kantō Soccer League club Tokyo United FC.[6] As this was an amateur contract, he worked part-time in a gym alongside playing football. Nagakura impressed on the pitch, scoring 8 goals in 9 appearances.[7] He finished as the league's joint top scorer, despite only playing for half the season.[8]
Thespakusatsu Gunma
In August 2022, Nagakura was offered a professional contract and transferred to J2 League club Thespakusatsu Gunma.[9] He would be joining up with manager Tsuyoshi Otsuki, who had previously coached Nagakura at Urawa Reds Youth. On 16 August 2022, he made his professional debut in a 1–0 league defeat to Yokohama FC.[10] He scored his first goal for the club in the following game, in a 1–0 league victory over Vegalta Sendai.[11] He finished the 2022 season with 2 goals in 6 appearances for Thespakusatsu Gunma.
In the 2023 season, Nagakura was a key member of the team and scored 5 goals in 20 appearances in the first half of the season.[12] At the end of July, it was announced that Nagakura would be joining J1 League club Albirex Niigata.[13]
Albirex Niigata
As Niigata's key player Ryotaro Ito transferred mid-season, the club was looking for forward reinforcements. Nagakura made his debut for Albirex Niigata on 12 August 2023, coming on as a substitute in a 2–2 league draw with Shonan Bellmare. He scored his first J1 League goal on the final game of the season in a 1–0 victory over Cerezo Osaka.[14] He renewed his contract in December 2023, ahead of the 2024 season.[15]
Nagakura finished the season as top scorer in the 2024 J.League Cup with 6 goals in 9 games, helping Niigata finish as runners-up in the competition.[17] He also made 30 league appearances, scoring 5 goals.
Urawa Red Diamonds
In January 2025, it was announced that Nagakura would be transferring to Urawa Red Diamonds, the club where he played the majority of his youth football.[18]