Liberal Democratic Party lawmaker and paternity leave trailblazer Kensuke Miyazaki on Friday quit his seat after admitting to an extramarital affair in a major blow to the push for reform to child care leave.

Speaking at a news conference, where he also gave a deep bow, Miyazaki said, "I am sorry that I have deepened voter distrust of politics by doing something that deviated from my promise."

"I have decided to step down as a lawmaker."