Tsuyoshi Watanabe was born on 5 February 1997 in Saitama, Japan. He came through FC Tokyo's youth ranks and won the J.League Cup with FC Tokyo in 2020–21. In January 2022 he moved to Belgium with KV Kortrijk, and in June 2023 he joined KAA Gent.
Watanabe's Gent career was productive. The 2023–24 season produced strong defensive output and 8 UEFA Europa Conference League matches with a goal and an assist. The 2024–25 season brought 34 Belgian Pro League matches with 2 goals and 2 assists, plus 1 cup match — his standout club year.
In July 2025 Feyenoord signed Watanabe in a major Eredivisie move. His Feyenoord debut season has been outstanding: 29 Eredivisie matches with 2 goals, 6 UEFA Europa League matches with a goal, 2 UEFA Champions League matches with 2 goals, and a KNVB Beker match — adding 5 European club goals as a defender, exceptional output.
For Japan, Watanabe has been a senior call-up since 2023, including 3 matches at the 2023 Asian Cup and 4 friendlies in 2025.
A 184cm two-footed centre-back with aerial presence, ball-playing security and the goal-scoring instinct from set pieces, Watanabe has been one of the most-discussed Japanese defenders in Europe. He is a strong candidate for the 2026 FIFA World Cup squad as a senior centre-back depth option.