Photo/Illutration Kentaro Sonoura talks to reporters in the Diet building in Tokyo on Nov. 30. (Hiroyuki Yamamoto)

Politician Kentaro Sonoura on Dec. 21 resigned from the Lower House and left the ruling Liberal Democratic Party to take responsibility for discrepancies in his political fund reports.

“I’m responsible, to a certain extent, for the erroneous records in my political fund reports,” Sonoura, 50, said in a statement. “The fact that I submitted income and expenditure reports with erroneous records about political funds, over which transparency is necessary, could invite public distrust in politics. I am truly regretful.”

About 40 million yen ($304,000) in income gained through fund-raising parties is believed to have been deliberately left out of Sonoura’s political fund reports.

On Dec. 21, he submitted his letter of resignation to Hiroyuki Hosoda, speaker of the Lower House, who accepted the resignation the same day.

The LDP also accepted Sonoura's application to leave the party on Dec. 21.

The Tokyo District Public Prosecutors Office is considering filing a summary indictment against Sonoura on charges of violating the Political Fund Control Law.

According to sources, investigators have recognized that Sonoura and his tax-funded aide conspired to underreport the political funds.

As a general rule, if Sonoura is convicted and his fine is finalized, he will be barred from running in elections for five years.

Sonoura told people around him that he intended to resign from the Diet before he is convicted in hopes that prosecutors would reduce the five-year suspension period based on his “cooperation” with the investigation, sources said.

A summary indictment would only become possible with Sonoura’s consent.

Sonoura has represented the Lower House’s No. 5 constituency in Chiba Prefecture.

A by-election to fill the now-vacant seat is expected in mid-April next year, in accordance with the Public Offices Election Law.

By-elections in the No. 1 constituency in Wakayama Prefecture and the No. 4 constituency in Yamaguchi Prefecture will also take place on that day to fill vacant Diet seats.

Sonoura is very close to LDP Vice President Taro Aso, a former prime minister, and was a member of his faction.

He served as vice minister of the Foreign Ministry and as a special adviser to the prime minister under the Shinzo Abe Cabinet.

More recently, Sonoura was chief director of the Lower House Judicial Affairs Committee.