Yuko Ohtsubaki

is a Japanese politician and labor activist. She was a member of the House of Councillors from 2023 to 2025, representing the Social Democratic Party (SDP), and served as a vice-chair of the party until 2026. She previously served as the chairperson of the Osaka Educational Workers' Union. She is married; her spouse is a Catalan from Barcelona.

Biography

Early life and education Otsubaki was born in Takahashi, Okayama Prefecture.

In 2002, she spent time studying informally on Negros Island in the Philippines.

Career In 2006, she was hired as a coordinator for students with disabilities at Kwansei Gakuin University on a fixed-term contract limited to four years. In 2010, she opposed the expiration of her contract and joined the Osaka Educational Workers' Union. She fought for reinstatement for three years and nine months but was not rehired. In 2016, she became chairperson of the union.

In 2020, she was appointed Executive Committee Member of the SDP National Association and Chair of the Labor, Women, and Diversity Policy Committee.

On April 12, 2021, she became a vice-chair of the Social Democratic Party.

On March 30, 2023, the House of Councillors accepted the resignation of Tadatomo Yoshida (Constitutional Democratic Party), who stepped down to run in the April 23 Oita Prefecture by-election. Since Yoshida was elected in 2019 as the top candidate on the SDP's proportional representation list, his replacement had to come from the SDP, not the CDP. The second and third candidates on the SDP list were no longer eligible (the second-ranked candidate, Mio Nakamura, had left the party in 2021 and joined the CDP ), so Otsubaki, who was ranked fourth and last on the list, was next in line for succession. On April 6, 2023, her succession to the House of Councillors was officially confirmed. In the 211th Diet session, she was assigned to the Committee on Agriculture, Forestry and Fisheries.

In the 2025 House of Councillors election, although she secured the second-highest number of individual votes within the SDP, the party managed to win only a single seat; consequently, she was defeated, as the seat went to LaSalle Ishii, who had garnered a higher number of individual votes.

In January 2026, the SDP announced it would endorse Otsubaki as a standalone candidate to run on the proportional representation list for the Tokyo block in the 2026 general election, scheduled for February 2026.

In the general election for the House of Representatives, the SDP failed to secure any seats in the Tokyo block, resulting in her defeat.

On February 27, 2026, Otsubaki apologized for a January 2026 statement she made opposing the SDP's endorsement of Chobin Zukeran in the Okinawa 2nd district. In the same apology, she announced her resignation as Deputy Party Leader of the SDP.

On March 4, Otsubaki announced her candidacy for the SDP leadership election. Ballots from the first round of voting were tallied on the 23rd, and since neither Otsubaki either of the other two candidates secured an absolute majority of the votes, a runoff election was scheduled to be held between the top two finishers: incumbent Party Leader Mizuho Fukushima (1st place) and Otsubaki (2nd place). Ballots from the runoff election where counted on April 6 where Otsubaki was defeated by Fukushima. During a press conference, party leadership denied Otsubaki the opportunity to speak, with Fukushima stating, "Today is my press conference regarding my assumption of office." Otsubaki protested this, saying, "That is outrageous; candidates should be treated equally," and stormed out of the room.

Policy positions Constitution

In a 2022 NHK questionnaire, Otsubaki stated that she opposes any revision of the Constitution. Regarding revision of Article 9, she told a 2022 Mainichi Shimbun survey that she opposes amending the war‑renouncing clause. In the same NHK poll she also opposed explicitly writing the Self‑Defense Forces into Article 9. she declined to answer in the NHK poll but told Mainichi Shimbun that the current sanctions are appropriate. Otsubaki said defense outlays "should be drastically reduced" in the NHK survey. She advocates "entry regulation" on non‑regular employment—that is, tightening the conditions under which employers can hire on non‑regular contracts.

Other issues

Asked about Japan's future reliance on nuclear power, she replied that it should be reduced to zero.