TOKYO — Koizumi Shinjiro was appointed minister of defense in the Takaichi Sanae administration following his defeat in the 2025 Liberal Democratic Party presidential election. Takaichi won the leadership contest after convincing LDP Diet members she could restore the party’s conservative direction.

Koizumi had been the overwhelming favorite to win the 2025 LDP presidential race according to polls and pre-election gatherings among Diet members. His campaign team even held a celebratory party the night before the result was announced, treating victory as certain. However, he significantly underperformed among rank-and-file LDP members and lost to Takaichi. A scandal involving his campaign team’s online dissemination of pro-Koizumi comments and disparaging remarks about opponents damaged his perceived authenticity, while his reliance on prepared remarks during debates and perceived inexperience contributed to his defeats in both the 2024 and 2025 elections.

Since becoming defense minister, Koizumi has set a goal to increase transparency into the ministry’s work and raise public awareness of Japan’s security environment. He and the Ministry of Defense have increased public outreach through various media, including long-form online programs and public announcements about foreign military activities near Japan. “Japan is facing the most severe and complex security environment since the end of World War II,” Koizumi said.

Koizumi has become Takaichi’s spokesperson for her defense policy, a role that has changed public perceptions of him. His advocacy of the administration’s policies has transformed his image and increased his credibility as a statesman. He is now being embraced by conservatives, a core LDP constituency he previously failed to court. His disclosure of China’s radar lock-on of Japanese jets contributed to the perception that he is tough on China.

Conservative figures have taken note of his shift. “Koizumi Shinjiro was an ‘awakened man’ and praised his expertise on the Japanese Maritime Self-Defense Force,” said Shinba Kazuya, secretary-general of the Democratic Party for the People. Hyakuta Naoki, head of the Conservative Party of Japan, shared the view that Koizumi has “awakened” since becoming head of the Defense Ministry. Koizumi acknowledged the trend, saying people had been saying he had “awakened” a lot. Japanese right-wing magazines Will and Hanada recently featured him on their covers alongside interviews with prominent conservative pundits.