In 1984, he completed his secondary education at Kaisei Academy and enrolled in the University of Tokyo's College of Arts and Sciences, where he majored in international relations.

[4] In 1989, Kiuchi entered the Japanese Ministry of Foreign Affairs, by which, in 1990, he was sent to the University of Augsburg, where he studied political science and worked on further improving his German.

Between 1996 and 2000 Kiuchi served as the official German-Japanese interpreter of Emperor Akihito, as well as prime ministers Ryutaro Hashimoto and Keizō Obuchi.

He says that they gave him the opportunity to speak with constituents in even the most remote parts of his electoral district and that "the economic hardship [he experienced] made him pick up a habit of keeping his feet busy.

He blames this imbalance on overly close ties between the corporate and the political world and vows to remedy the situation by separating the spaces within which small and large businesses are meant to thrive.

Kiuchi calls for an expansion of Japan's primary sector, through which he intends to increase Japan's rate of food self-sufficiency of currently only 40% (based on caloric intake), preserve rural landscapes, make accessible new sources of fresh water, and secure areas otherwise prone to natural disasters such as landslides.

While affirming the necessity of solutions on a macro-level, such as R&D and the reduction of CO2 emissions and energy consumption, Kiuchi proposes further action on a local and individual level, such as recycling, volunteer activities, and a change in people's lifestyles and way of thinking.

In a joint letter initiated by Norbert Röttgen and Anthony Gonzalez ahead of the 47th G7 summit in 2021, Kiuchi joined some 70 legislators from Europe and the US in calling upon their leaders to take a tough stance on China and to "avoid becoming dependent" on the country for technology including artificial intelligence and 5G.

[15] Kiuchi praises Japan's social security and health care institutions, which, he says, offer support to the weaker members of society and make advanced medical treatment available to everyone.

[16] He regularly hosts German politicians in Japan, for whom he arranges meetings with their political counterparts, such as between parliamentary group leader Volker Kauder and Japanese prime minister Shinzō Abe in March 2018.

[16] In August 2019, retired senior politician Shizuka Kamei dedicated an issue of his serialized editorial on Japanese politics to Kiuchi's opposition to the privatization of Japan Post.

In late 2005, prime minister Jun'ichirō Koizumi ran for re-election using slogans such as "from bureaucrats to the people (官から民へ)" and "where there is no reform, there is no growth (改革なくして成長なし)."

Kiuchi staunchly opposed the privatization, despite being a member of Seiwa Seisaku Kenkyūkai, prime minister Koizumi's own faction within the LDP.

Resisting party-pressure, Kiuchi stood by his initial stance and voted against the privatization, which led to him temporarily parting ways with the LDP.

"[18] Kiuchi was visiting Europe in his capacity as parliamentary vice-minister for foreign affairs when the In Amenas hostage crisis erupted.

After the Japanese government heard of the attack, Kiuchi was ordered to redirect his trip to Algeria to lead the negotiations on behalf of Japan.

The team of political commentators described Kiuchi as strong in both his actions and speech, as well as quick-witted thanks to his past experience as a diplomat.

[24] In 2020, an opinion piece featured in the American news magazine Newsweek described Kiuchi as a "top candidate" for the next race for the premiership.