Tatsuki Seko

Yokohama FC Seko officially joined Yokohama FC on 13 January 2020. He made his J1 League debut on the opening day against Vissel Kobe, scoring in a 1–1 draw, which was Yokohama's first top-flight goal for 13 years. Seko played 36 times in the 2020 J1 League season as relegation was scrapped due to the COVID-19 pandemic and Yokohama finished in 15th place. In the 2021 season Seko played 38 times as Yokohama were relegated finishing in 20th.

Kawasaki Frontale

Following Yokohama's relegation Seko was reported to be wanted by J1 League clubs Nagoya Grampus and Sanfrecce Hiroshima. Eventually league champions Kawasaki Frontale signed Seko on 23 December 2021. He made 19 appearances in the 2022 season as Kawasaki missed out on the league title by two points to Yokohama F. Marinos. In the 2023 season, Seko played 39 times as Frontale finished in 8th position and won the 2023 Emperor's Cup after beating Kashiwa Reysol in the final on penalties. Seko was captain as Kawasaki Frontale defeated Vissel Kobe 1–0 in the 2024 Japanese Super Cup. It was announced by Frontale in August 2024 that Seko had left the team to complete a move abroad.

Stoke City Seko signed a three-year contract with EFL Championship club Stoke City on 30 August 2024. Seko made 28 appearances in the 2024–25 season, as Stoke avoided relegation on the final day, finishing in 18th position. Seko played a lot more regularly in 2025–26, making 47 appearances as Stoke again finished in a bottom half position of 17th.

Urawa Red Diamonds After two seasons playing in English football, Seko returned to Japan in August 2026, signing for Urawa Red Diamonds.

Career statistics .

Honours Kawasaki Frontale Emperor's Cup: 2023 Japanese Super Cup: 2024