Japan's Diet is set to open an ordinary session on Friday, that is overshadowed by a political funding scandal involving factions of Prime Minister Kishida Fumio's Liberal Democratic Party.

The prime minister was due to deliver his annual policy speech on the first day of the session. Instead, he will do so on Tuesday, a day after lawmakers hold committee deliberations over the issue of politics and money.

Three LDP factions, including one that Kishida formerly led, are suspected of failing to declare some revenue from fundraising events and giving kickbacks to members.

Ten people, including three current and former lawmakers, are facing charges over the allegations.

Most of them were in the LDP's largest faction, once led by late Prime Minister Abe Shinzo.

Ten Diet committee chairs and one council chair, who are members of the faction, will be replaced at the start of the session.

Opposition forces appear ready to call for Kishida and other LDP lawmakers involved in the scandal to testify.

The government and the LDP, on the other hand, are expected to stress that they will seek to restore the people's trust by implementing the proposals of an interim report compiled by an LDP taskforce on Thursday.

Governing and opposition parties are also studying how to revise the political funds control law to improve the transparency of money flows.

Proposals currently under consideration include lowering the minimum amount of money requiring the names and other information of fundraising ticket buyers to be registered in political funds reports.

Another proposal calls for lawmakers to be held accountable if their treasurers are charged with wrongdoing.

The opening ceremony of the Diet session will take place on Friday afternoon, with Emperor Naruhito attending. The session will run for 150 days through June 23.