With members of the ruling Liberal Democratic Party (LDP) failing to provide clear answers during voluntary testimony about a political funds scandal, Prime Minister Fumio Kishida faces increased pressure to take tougher measures, including having them testify under oath, during which they would face legal penalties for perjury.

If that weren’t difficult enough, Kishida must also make tough political choices soon on punishments for more than 80 LDP members caught up in the scandal, including party heavyweights.

On Tuesday, four opposition parties — the Constitutional Democratic Party of Japan (CDP), Nippon Ishin no Kai, the Democratic Party for the People and the Japanese Communist Party (JCP) — issued a joint call for six Lower House current and former LDP members to give sworn testimony to the Diet — the formal name of Japan's parliament — on what they knew about the political funds scandal.