Takeshi Tokuda has stepped down as parliamentary secretary for land, infrastructure, transport and tourism for "personal reasons," Chief Cabinet Secretary Yoshihide Suga said Monday.
Tokuda is the first parliamentary secretary in the Cabinet established by Prime Minister Shinzo Abe following the general election in December to resign.
Political sources hinted that Tokuda, 41, who was also parliamentary secretary for reconstruction from the 2011 earthquake and tsunami, was embroiled in troubles with a woman.
Suga said Tokuda's resignation was accepted by Abe and that his successor will be picked within the week.
After winning a Diet seat for the first time in 2005 representing the No. 2 constituency of Kagoshima Prefecture, Tokuda joined the Liberal Democratic Party the following year, according to his website. He is now serving his third term in the House of Representatives.
His father, Torao Tokuda, is a retired lawmaker who served as the leader of now-defunct political party called the Liberal League.