An election management office in Aichi Prefecture has been bombarded with irate calls and emails claiming Sunday's re-election of independent lawmaker Shiori Yamao — who was forced to leave the Democratic Party last month amid allegations of an extramarital affair — was illegitimate.

Yamao, whose aggressive questioning style has made her a prominent adversary of Prime Minister Shinzo Abe at Diet debates, beat local rival Junji Suzuki, of the ruling Liberal Democratic Party, by a razor-thin margin of 800 votes in the election.

Yamao became the target of criticism last month when a weekly tabloid alleged that she was involved in an extramarital affair. The lawmaker and mother denied she had ever committed adultery but left the party nonetheless.