On 6 June 2008, Hasegawa signed a professional deal with Marinos, and scored his first senior goal on 29 November, netting the last in a 2–0 home success against Tokyo Verdy.
Hasegawa formalized his professional partnership with Marinos on June 6, 2008, and then achieved his first senior victory with a goal on November 29, securing the last score in a 2–0 home win against Tokyo Verdy.