In January 2024, amidst a slush fund scandal involving LDP politicians, he was summarily indicted on charges of failing to disclose political kickbacks.

Prior to his resignation from the LDP during the 2023–2024 Japanese slush fund scandal, Tanigawa was a member of the Seiwa Seisaku Kenkyūkai, closely associated with Prime Minister Shinzo Abe.

[6] In May 2019 Tanigawa acquired attention after complaining of his frustration regarding the construction of the Nishi Kyushu Shinkansen, comparing negotiations over the project to "dealing with South or North Korea."

[7] On 9 January 2024, amidst a broader scandal in the LDP, allegations began to emerge that Tanigawa had received ¥40 million in kickbacks from the Seiwa Seisaku Kenkyūkai,[5] along with his secretary.

[5] Three days later, after he was formally indicted by Tokyo Police (alongside Yasutada Ōno) for violating the Political Funds Control Act [ja], Tanigawa announced his resignation from the LDP and publicly apologised.