[6] A native of Kisarazu, Chiba and graduate of Waseda University, Matsuno originally wanted to work in the film industry but instead took a job in advertising at Lion Corporation.

[8] Affiliated to the openly revisionist lobby Nippon Kaigi,[9] along with most members of the Abe cabinet, Matsuno denies the existence of the Imperial Japan sex slavery system known under the euphemism 'Comfort women',[6] and in 2014 demanded the revision of the Kono and Murayama statements, considered as landmark declarations from Japanese governments towards the recognition of war crimes.

[4][5] In a 2023 press conference, he stated that there was insufficient evidence for the event, directly contradicting a 2009 expert panel of the government's Central Disaster Management Council.

[12] The following day, multiple news outlets reported that Prime Minister Fumio Kishida was preparing to replace Matsuno as Chief Cabinet Secretary.

[13][14] On December 12 the lower house, of which the LDP holds a majority, voted down a motion of no confidence against Matsuno that had been put forward by the opposing Constitutional Democratic Party of Japan.