All eyes are on former Liberal Democratic Party policy chief Hakubun Shimomura as he prepares to give voluntary testimony to a Lower House political ethics committee Monday on how his faction approved unreported kickbacks to its members.

As the party continues to grapple with the fallout from a political slush funds scandal involving members of the faction previously led by former Prime Minister Shinzo Abe, formally known as the Seiwakai, Shimomura's answers could clarify — or obscure — what happened and why.

The scandal saw members receive off-the-books funds from senior Abe faction leaders for sales of fundraising party tickets exceeding their set quota.

Shimomura's role in the scandal is currently unclear. But he served as secretary-general of the Abe faction between January 2018 and September 2019 and continued as a senior faction leader after that.

The focus of Monday’s questioning is expected to center on what happened between April 2022, when Abe recommended to the faction leadership that the kickback system be abolished, and August of that same year — a month after Abe’s assassination — when the faction decided to continue the scheme.

Shimomura was one of the senior leaders present at the April 2022 meeting. But following Abe’s death in July 2022, he was excluded from the restructured faction leadership adopted in August.

Four members of the restructured faction leadership have denied any involvement in the scandal in their testimonies before a previous Lower House ethics committee. They said they did not know exactly how the faction leadership decided to continue the scheme despite Abe’s wishes.

Another leader, former LDP Upper House Secretary-General Hiroshige Seko, told an Upper House political ethics committee the same thing on Thursday.

Shimomura is the last remaining former Abe faction secretary-general who has not provided parliament with a testimony on what he knew and when he knew it.

In addition to the spotlight on his own role, Shimomura’s testimony Monday could shed light on what part, if any, that former Prime Minister Yoshiro Mori had in the decision-making process. Mori once headed the Seiwakai.

One of the leaders, former education minister Ryu Shionoya, told the committee that the kickback scheme started about 20 years ago. That was between 1998 and 2006, when Mori chaired the faction.

Though he retired from politics in 2012, Mori remained an influential presence in the faction, and he and Shimomura do not get along.

Some wonder whether Shimomura’s exclusion from the faction leadership team after Abe’s death was due to their rivalry.

There are growing calls within the LDP to query Mori over his possible involvement in the scandal, and Shimomura’s answers Monday could increase the pressure on the former prime minister to break his silence.

Prime Minister Fumio Kishida, however, appears to be cautious about that possibility. While he, as LDP president, has said that the party would discuss hearing directly from those involved, he did not offer specific examples of who he had in mind.

Shimomura has told the media that after Abe’s death, the kickbacks were consequently made by the faction's secretariat in accordance with the past practice though he denied being involved.

“I was the acting president of the Seiwakai at that time (of Abe’s death). But I never instructed or approved the non-reporting of the income,” Shimomura said at a news conference on Jan. 31.

The Abe faction made donations to 95 Diet member organizations totaling ¥676.54 million ($4.6 million) between 2018 and 2022. Of this amount, ¥427.42 million was donated to the political organizations of individual Diet members in 2020-22, but was omitted from legally required political funds reports.