From October 6 to 10, 2025, a delegation of California mayors, county officials, and civic leaders traveled to Japan to participate in the Japan–United States Leadership Summit, a high-level international program organized by the Japan–United States Sister City Association (JUSSCA), with California Sister Cities organizing the California delegation.

The delegation program began in Osaka with visits to Expo 2025, where participants explored global innovations in sustainability, artificial intelligence, and smart-city development. California Sister Cities worked closely with local member cities and partner organizations to coordinate participation by municipal leaders and ensure broad regional representation from across California.

According to California Sister Cities Chair and the head of the delegation, Dr. Anthony Al-Jamie, “This has been an amazing experience for all of the mayors and county officials. We experienced the true meaning of omotenashi at each and every stop along the way. This exhilarating and perspective-changing experience had a tremendous impact on the delegation. It began with Expo 2025 Osaka, where we experienced the world coming together under the organization of the host country, Japan, which did an incredible job of efficiently operating one of the most complex and ambitious undertakings of any event in the world this year. Not only did the delegation have the opportunity to view all of the cultural festivities and innovative solutions presented, but we also had the privilege of seeing the Emperor and Empress drive through the crowd. Just being at the Expo on the same day as the Emperor and Empress was truly an unforgettable experience that I will cherish forever.”

Warm Welcome from Kansai Mayors

On the evening of October 6, the delegation was warmly welcomed by mayors from across the Kansai region. “Through their heartwarming speeches, we could feel the true warmth and energy that the Mayors of Kansai brought,” said Dr. Al-Jamie.” Berkeley Mayor Adena Ishii noted the significance of beginning the trip in Osaka, sharing, “Berkeley has a long-standing relationship with Sakai City, our Japanese sister city [located in Osaka Prefecture]. I was very excited to meet Mayor Hideki Nagafuji of Sakai and present him with gifts from Berkeley, including a Visit Berkeley magazine in Japanese. Meeting other Japanese mayors and dignitaries at our Summit’s evening dinner and visiting Expo 2025 Osaka before it closes was an amazing experience. We were also able to visit the U.S. Pavilion activation, which showcased the country’s milestones and space initiatives.”

Sausalito Councilmember Jill Hoffman also strengthened ties with their sister city located near Osaka, saying, “I was honored to meet with Mayor Tetsuji Arifuku of Sausalito’s Sister City, Sakaide, Japan. We discussed several sustainable initiatives, including transitioning an oil refinery to hydrogen energy and a pilot program for driverless electric public buses.”

City of Carson Mayor Lula Davis-Holmes reflected on the delegation’s introduction to Japan’s innovative spirit: “The California delegates kicked off the visit by touring the Japanese Expo, which featured cutting-edge technology from around the world.” Her colleague, City of Carson Councilmember Arleen Rojas, emphasized the importance of partnership, saying, “Collaboration is power! Thank you to the Japan–U.S. Leadership Summit for sharing the official goals of Expo 2025 Osaka, Kansai, Japan. The World Expo is an international exhibition of each country’s latest and best inventions and innovations. We are grateful for the opportunity to connect, learn, and share ideas as we look forward to continued collaboration ahead.”

Fuji–California Leaders Summit hosted by Yamanashi and Shizuoka Governors
The delegation then traveled by bullet train to Shizuoka and on to Yamanashi, where they were greeted by Shizuoka Governor Yasutomo Suzuki and Yamanashi Governor Kotaro Nagasaki, along with Fuji–California Leaders Summit Chair Dr. Hiroshi Tasaka at the Kawaguchiko Music Forest Museum. The group toured the Komekurayama Green Hydrogen Facility, gaining first-hand insight into Yamanashi Prefecture’s leadership in clean energy and hydrogen innovation.

Berkeley Mayor Adena Ishii reflected, “We heard presentations from Yamanashi Prefectural government officials regarding green hydrogen initiatives & research on medical devices. I had a one-on-one session with Yamanashi Governor Kotaro Nagasaki & Dr. Hiroshi Tasaka, a prominent Japanese author and former Special Advisor to the Japanese Prime Minister, where we discussed opportunities for collaboration between Berkeley and Yamanashi.”

Fairfield Mayor Catherine Moy added, “I met one-on-one with Dr. Hiroshi Tasaka and Yamanashi Governor Kotaro Nagasaki to discuss how we can bring technology for zero-carbon hydrogen fuel to Fairfield and also trade in Suisun Valley’s products. I will sign on to some initiatives to bring our youth together through art. We’re making huge progress in building diplomatic and business ties.” She added, “I’ve learned so much from colleagues, government officials, Japanese citizens, academic officials, business people, and many youth. I’m beyond honored to have had the chance to represent my hometown on the world stage.”

United Nations University in Tokyo
The Summit concluded with two days of keynote presentations and dialogue at United Nations University (UNU) in Tokyo, where U.S. and Japanese leaders shared initiatives advancing sustainable cities, digital transformation, and cross-cultural collaboration.

Featured speakers included Tokyo Governor Yuriko Koike, Former Foreign Minister and Minister for Digital Transformation Taro Kono, Architects Shigeru Ban and Paul Noritaka Tange, former Japan Ambassador to the U.S. Kenichiro Sasae, and UNU Rector Dr. Tshilidzi Marwala, alongside U.S. civic leaders presenting local innovations in sustainability and community development.

Governor Koike urged stronger multi-city cooperation and resilience, outlining Tokyo’s Green Biz and AI Strategy 2025 initiatives for sustainable, tech-driven urban growth. She reflected on the historic friendship between the two nations: “The U.S. and Japan have enjoyed a strong, long-standing friendship that has been enriched by deepening exchanges across 171 years… As longstanding partners, the United States and Japan must join hands to forge a bright future filled with hope. While deepening ties with the United States, Tokyo will take the initiative in working to solve global challenges.”

Berkeley Mayor Adena Ishii shared her reflections on the Summit’s closing days: “As the youngest mayor in our delegation, and as a Japanese American, it was an honor to represent Berkeley in an international setting, promote tourism, and encourage business collaborations. We are positioning Berkeley as an environmental leader with much potential for partnership with Japan. At the United Nations University, I spoke on ‘Building Consensus,’ a topic I find extremely valuable during these critical times. It was an honor to share the stage with Tokyo Governor Yuriko Koike and other global leaders advancing sustainability and innovation.”

Governor Koike’s message of shared responsibility and innovation resonated throughout the Summit. Shigeru Ban and Paul Tange explored the intersection of architecture, community, and sustainability, while Dr. Marwala highlighted AI’s potential to create equitable, connected global cities, stating, “Strengthening city-level ties is vital for sustainable and inclusive futures”. A demonstration by Mobeon Tokyo CEO Daishi Takiishi showcased emerging AI-powered urban technologies.

To mark the new strategic partnership between the United Nations University and the Japan–United States Sister City Association, JUSSCA Chairman Shin Koyamada noted, “The Summit served as a platform to explore cross-cultural partnerships and identify pathways for local and global development.”

A special tribute organized by Anaheim University honored the late sustainable architect Dr. Kisho Kurokawa (1934–2007). The memorial featured JUSSCA Chair Anthony Al-Jamie, Dial Service CEO Yuri Konno, and Mikio Kurokawa, along with a tribute video by the Anaheim University Kisho Kurokawa Green Institute, celebrating Kurokawa’s enduring legacy of ecological design and his philosophy of “symbiosis” in architecture.

The Delegation
The California delegation, who presented their city initiatives, included: Lula Davis-Holmes, (City of Carson Mayor), Arleen Rojas City of Carson Councilmember), Adena Ishii (Berkeley Mayor), Kelly Cox (Santa Clara Vice-Mayor), Luis A. McArthur (Oxnard Mayor), Joshua Sweeney (Laguna Hills Mayor), Catherine Moy (Fairfield Mayor), Kim Bowman (La Cañada Flintridge Mayor), Mona Miyasato (Santa Barbara County Executive Officer), Oscar Gutierrez (Santa Barbara City Councilmember), Tania Sheyner (San Francisco Principal Environmental Planner), Jill Hoffman (Sausalito Councilmember), John Wu (San Gabriel Councilmember), Jon Kaji (Torrance Councilmember), Martha Guerrero (West Sacramento Mayor), and Ara Najarian (Glendale Mayor).

The Summit, which held a welcome reception at UNU on Oct. 9, concluded with a Sayonara Reception on Oct. 10, featuring a kimono show with live jazz and shamisen performances, celebrating strengthened sister-city partnerships and shared commitments to climate resilience, digital inclusion, and intercultural understanding. Dr. Al-Jamie stated, “These receptions couldn’t have been done without the important support of the U.S.-Japan Foundation and the Japan Foundation’s CULCON.”

Reflecting on the presentations, Santa Barbara County Executive Officer Mona Miyasato shared, “I was so excited to hear from the acclaimed Japanese architects Shigeru Ban and Paul Tange, who shared their invaluable insight with us.”

San Gabriel City Councilmember John Wu noted that several Japanese cities expressed interest in forming friendships with San Gabriel and shared an inspiring message, emphasizing that few nations offer immigrants like himself the opportunity to serve as public officials.

West Sacramento Mayor Martha Guerrero expressed her gratitude for the experience: “I enjoyed the culture and the history as we walked around that beautiful [Hotel New Otani Tokyo] garden. It is such an incredible experience being here in Japan, and I am so thankful to the foundation, partners, and our host, Dr. Anthony Al-Jamie, for all the hard work that went into this. And to United Nations University, Dr. Marwala, for opening up your space for us to be present—it is such an honor.”

Building on that spirit of appreciation, Santa Barbara City Councilmember Oscar Gutierrez shared, “This trip was a once-in-a-lifetime experience, and I am so appreciative and grateful to the Japan–United States Sister City Association and the Japanese government.” His remarks echoed the gratitude expressed by fellow delegates and underscored the powerful sense of connection felt throughout the Summit.

Fairfield Mayor Catherine Moy later reflected on her experience in Tokyo, saying, “What a city! I’ve been to Paris, Chicago, LA, Dallas, New York, Seattle, and more—but Tokyo has more bustle, energy, and flavor, all amid its deep sense of ancient culture.”

Adding a reflective note to the Summit, Mason Granger, Poet-in-Residence at the University of Southern California Schwarzenegger Institute for State and Global Policy, who cited poetry during presentations and receptions in Yamanashi and Tokyo, felt, “We may look at the water from different sides, but at the end of the day, it’s the same ocean.” His words captured the spirit of unity that defined the Japan–U.S. Leadership Summit—bridging cultures, cities, and ideas through dialogue and shared purpose.

The October 6-10, 2025, Japan-United States Leadership Summit was organized by the Japan–United States Sister City Association (JUSSCA) and California Sister Cities, and sponsored by the United Nations University (UNU), United States–Japan Foundation, Japan Foundation’s CULCON, and Attain Corporation.