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Will Koizumi Shinjiro Become Japan’s Youngest Prime Minister?

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Will Koizumi Shinjiro Become Japan’s Youngest Prime Minister?

The former environment minister is leading in the polls, despite being just 43 years old. What would his election mean for the LDP and Japan?

Will Koizumi Shinjiro Become Japan’s Youngest Prime Minister?

Former Japanese Environment Minister Koizumi Shinjiro (to the left of the surfboard) and U.S. Ambassador to Japan Rahm Emmanuel (to the right of the surfboard) during the All-Japan Class Surfing Championships in Fukushima, Japan, July 6, 2024.

Credit: U.S. Embassy Japan

On September 6, Koizumi Shinjiro, former environment minister and the son of former Prime Minister Koizumi Junichiro, officially expressed his willingness to run in the Liberal Democratic Party (LDP)’s upcoming presidential election. It is his first effort to seek the party’s top post – and, by extension, the role of Japan’s prime minister.

Sitting Prime Minister Kishida Fumio has already announced that he will not run in the next LDP presidential election. Voting and vote counting will be held on September 27. If Koizumi, 43 years old, is selected as the next LDP president, he will become the youngest prime minister in the history of Japanese politics.

According to a poll of LDP supporters conducted by Nikkei and reported on August 23, Koizumi was the most popular choice as the next LDP president with 32 percent support, followed by Economic Security Minister Takaichi Sanae with 15 percent, and former LDP Secretary-General and former Defense Minister Ishiba Shigeru with 14 percent. Even among respondents who do not support any specific political party, the poll showed that Koizumi was the first choice with 20 percent support, with Ishiba in second at 17 percent. 

On the other hand, another poll by Kyodo reported on August 19 had Ishiba as the top choice with 25 percent, followed by Koizumi with 19 percent, and Takaichi with 10 percent. Still, among the LDP supporters, Koizumi was in first with 24 percent, and Ishiba was second with 21 percent. 

The recent opinion surveys indicate that a plurality of both LDP supporters and the Japanese people at large believe that Koizumi Shinjiro should become the next Japanese prime minister. Notably, unlike Ishiba, Koizumi had not announced his bid for the presidential campaign at the time of the polls. It is likely that Koizumi’s support will be higher now that he has officially declared his candidacy. 

If Koizumi becomes the next president of the LDP, the leadership change would be beneficial for the party, which has suffered from scandals resulting from the mingling of politics and money. The issue has become one of the main agenda items in current Japanese politics. Even the LDP supporters have felt betrayed by the party’s financial scandals, which could be seen as the “old image” of the party. 

In order to remove the old image and replace it with a “new image” – thereby giving a “sense of renewal” (sasshin-kan) to voters – the LDP would need to select a president who embodies this new image.

Another new face, 49-year-old former Economic Security Minister Kobayashi Takayuki, has already announced his bid for the LDP presidential election as well, but he is less popular than Koizumi. 

As shown in the recent opinion polls, Koizumi has the public support to be the “new face” of the LDP in preparation for the next general election, which could be held immediately after the LDP’s presidential election and must be held by fall of 2025. As a young candidate, Koizumi has come to embody the sense of generational change within the LDP. 

Koizumi, however, has some weaknesses as a candidate for the LDP president. Leading criticisms of Koizumi are that he lacks experience in both domestic politics and foreign affairs, and he is too young to be the prime minister. 

It is true that Koizumi, 43, seems young for the top leader role of Japanese politics. In postwar Japan, the youngest prime minister to date was Abe Shinzo, who was 52 when he assumed office for the first time. However, Koizumi has more experience than his age might imply. 

He started his political experience as a secretary to his father, former Prime Minister Koizumi Junichiro, in 2007. Then he was first elected to parliament in 2009, at the age of 28, and was re-elected five times in a row. Koizumi Shinjiro became parliamentary vice-minister of the Cabinet Office and parliamentary vice-minister for reconstruction in 2013. In 2019, he was selected as minister of the environment and minister of state for nuclear emergency preparedness, and served until 2021 during the administration of former Prime Minister Suga Yoshihide. Suga is now a strong supporter of Koizumi’s presidential election campaign. Therefore, Koizumi already has a great deal of experience in the Cabinet Office for his age. 

Looking farther back in Japan’s history, in 1885 Ito Hirobumi became the first Japanese prime minister at the age of 44, and served as the prime minister four times in total. But Koizumi has another political hero in mind: J. F. Kennedy, who assumed the U.S. presidency at the age of 43 – incidentally, the same age as Koizumi is now. It has been reported that Koizumi’s parliamentary office is decorated with pictures of Kennedy. Few Japanese and American people might think that Ito and Kennedy were too young or immature for the roles as top leaders of the countries.

As an example of Koizumi’s image as inexperienced, some point to his “sexy” gaffe as environment minister. Koizumi told a news conference in New York on September 22, 2019, “In politics there are so many issues, sometimes boring. On tackling such a big-scale issue like climate change, it’s got to be fun, it’s got to be cool. It’s got to be sexy too.” 

Koizumi’s “sexy” remark confused the Japanese audience. Many people in Japan saw it as a political gaffe by an inexperienced minister. In the words of one Japanese university student and environmental activist: “We had hopes for Koizumi because his age is closer to us, but he didn’t respond well… He said ‘sexy’ and it didn’t really make sense… As one Japanese citizen, I am embarrassed.”

However, the remark on making climate change “sexy” was not original to Koizumi. Instead, he was inspired by a Costa Rican diplomat, Christiana Figueres, who served as a chief of the United Nations Framework Convention on Climate Change (UNFCCC). Figueres had stated that “it is time to make green sexy.” 

In Japan, it is still a taboo to publicly talk about sex, and most Japanese people might hesitate to say the word in public. In addition, most Japanese people do not know that the term “sexy” can simply mean “interesting” or “exciting” in English. For these reasons, Koizumi should have explained that he was citing Figueres, a U.N. diplomat, as background information to Japanese audiences.

Another weakness of Koizumi is the fact that he is a hereditary politician, which feeds into the “old image” of Japanese politics. Indeed, Koizumi Shinjiro is from a famous political family – his father, Koizumi Junichiro, served as prime minister from 2001-2006, and his grandfather, Koizumi Junya, was a lawmaker who served as director general of the Defense Agency (the equivalent to today’s defense minister) from 1964-1965. Koizumi Shinjiro’s great-grandfather, Koizumi Matajiro, was also a popular politician who had served as a minister of communications and a mayor of Yokosuka. 

For Koizumi Shinjiro, his status as a hereditary politician could be a disadvantage in the middle of the current political agenda in Japan, namely weeding out the “politics and money” nexus. On the other hand, the family tradition, especially his father’s legacy, is a key point of his popularity.

If Koizumi becomes the next Japanese prime minister, he will bring to office a strong familiarity with the United States, Japan’s only treaty ally. After graduating from Kanto Gakuin University in 2004, Koizumi decided to study in the United States. He went to graduate school at Columbia University where he majored in politics and obtained a master’s degree in 2006. Koizumi then worked as a part-time research associate of the Center for Strategic and International Studies (CSIS) in Washington. 

Given his background, Koizumi will attempt to strengthen Japan-U.S. relations in both foreign and defense policy. He developed a personal network with American policymakers and researchers during his time at CSIS in Washington.

On July 6, Koizumi and U.S. Ambassador to Japan Rahm Emanuel inspected Fukushima and expressed their support for the maritime discharge of treated wastewater from the Fukushima nuclear power plant. Koizumi and the ambassador enjoyed surfing on the beach of Fukushima and tasted sashimi made from Fukushima’s fish, sending a diplomatic signal toward China (which has banned imports of seafood from Japan) regarding the safety of the treated water.

His father, Koizumi Junichiro, was famous for his political stance that strengthened Japan’s foreign and defense policy in cooperation with Washington by exercising a top-down style of decision-making, which was called Koizumi diplomacy. If elected as the next Japanese prime minister, Koizumi will undoubtedly reinforce the Japan-U.S. relationship through a new Koizumi diplomacy.