[3] Sekigawa played 4 times in the competition, as well as another 8 games in the Prince Takamado Trophy JFA U-18 Football League.
[5] Sekigawa started all five games and was one of the driving forces behind the victory – drawing some comparisons to Kashima Antlers centre-back Naomichi Ueda.
[12] In April 2019, Sekigawa made his professional debut for Kashima in a 0–1 AFC Champions League defeat to Gyeongnam FC.
Following the departures of defenders Tomoya Inukai and Koki Machida before the start of the 2022 season, Sekigawa was handed the number 5 shirt was afforded much more playing time.
[23] In 2019, he was called-up to replace the injured Ryotaro Tsunoda as part of the U-20s Chiba training camp before the 2019 FIFA U-20 World Cup, although Sekigawa did not make the squad for the tournament.