The company, whose restaurants selling "gyudon" beef bowls are normally popular among salarymen and students on a tight budget, said it was stepping up efforts to boost takeaway sales but forecast a full-year operating loss of 8.7 billion yen as people work from home and avoid socialising.

Japan has largely avoided the mass infections that have killed tens of thousands overseas, but a surge in cases during the past week in Tokyo and other major urban areas has experts worried the country faces a second wave.

(Reporting by Ritsuko Ando)