Ryuji Kimura filed a suit in Kobe district court last June, claiming he could not run for the election due to his age and inability to prepare a ¥3 million (US$22,339) deposit, Yomiuri newspaper and other outlets said, citing the case record.

According to the record, the 24-year-old Kimura claimed the election law violates the Constitution, which stipulates equality under the law among other provisions.

The court dismissed the claim, in which Kimura sought ¥100,000 in damages for the mental anguish he allegedly had suffered, according to the reports.

Kimura appealed to the Osaka High Court against this ruling with more claims that incumbent political forces were unlawfully remaining in power, and a decision is scheduled next month, Japanese media said.

Japanese authorities searched Kimura’s home on Sunday in Kawanishi in Hyogo prefecture a day after he was arrested on the scene after allegedly trying to attack Kishida with an explosive object during an election speech by the premier in the city of Wakayama.

Kimura has yet to be formally charged over the incident.

To tighten security after the incident, Kishida’s government and the ruling Liberal Democratic Party decided to move high-profile campaign speeches to indoor venues and conduct baggage inspection until Sunday’s election, Jiji news reported.

The incident raised alarming questions about the state of VIP security in Japan, less than a year after former premier Shinzo Abe was shot to death and a month before Japan hosts Group of Seven (G7) leaders.

Kishida has vowed to ensure the safety of G7 dignitaries visiting the country.