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's professional affiliation with Marinos was formalized on June 6, 2008, and he achieved his first senior success with a goal on November 29, securing the final score in a 2–0 home triumph over Tokyo Verdy.