![What Is a Smart City for Citizens? — Seoul, Barcelona, and Tokyo on the Frontier of "Human-Centered AI Cities" [SusHi Tech Tokyo 2026]](/images/columns/smart-cities-evolving-for-citizens-2026/cover.png)
Hello, this is Hamamoto from TIMEWELL. "What exactly is 'smart' about a smart city?" — when Professor Yuji Yoshimura of the University of Tokyo's Research Center for Advanced Science and Technology, serving as moderator, opened the Smart Cities session at SusHi Tech Tokyo 2026 with that root-level question, the air in the room visibly tightened. I straightened my back at that prompt, because the question is continuous with what we do at TIMEWELL.
The session featured Kang Jeong-han, Director General of Seoul Metropolitan Government's Digital City Bureau, Maria Bigas, Chief Architect of the Barcelona City Council, and Professor Deguchi of the Graduate School of Frontier Sciences at the University of Tokyo. The 90 minutes in which three city representatives each described their own implementations sharply increased the resolution of the term "smart city"[^1].
What made this lineup unusual was the deliberate mix of practitioner and theorist. Kang and Bigas are the people pressing the buttons on actual budget lines and real procurement decisions, while Professor Deguchi brings the long-arc framing of how a city's data architecture coheres over decades. That combination is what made the session more than a standard set of country presentations. Each speaker was, in effect, holding the others accountable to a slightly different standard — implementation reality on one side, design rigor on the other. Sessions structured this way are rare in Japan, and the texture of the discussion benefitted from it.
Event Background — Why SusHi Tech Became the "City × Startup" Crossroads
SusHi Tech Tokyo 2026 is Asia's largest global innovation conference, running April 27-29, 2026 at Tokyo Big Sight. The event hosts 770 startups, and starting this year, it is co-located with G-NETS (Global Network of Tokyo Summit), a mayoral-level summit of cities worldwide[^2][^3]. The private startup ecosystem and the public ecosystem of city administrations now meet face to face under the same roof — that is what SusHi Tech has become.
What this session symbolizes is a clear shift: "Smart cities are no longer technology showcases — they are platforms for implementing citizen well-being." Over the past decade, "smart city" was too often spoken of in expo-style presentations stitching together sensors, dashboards, 5G, and blockchain. That has clearly changed. The subject of the conversation has migrated from "technology" to "citizens."
For a report on the Special Keynote by Governor Koike and Prime Minister Takaichi, held at the same venue, see SusHi Tech Tokyo 2026 Keynote Report | Governor Koike and Prime Minister Takaichi on the Seriousness of Building a "Startup Nation Japan". National startup strategy and the city OS debate are tightly intertwined.
It is also worth recognizing why this co-location is happening at this particular moment. In the previous decade, smart-city budgets were largely controlled by national ministries and a handful of consulting firms. The procurement gravity has now visibly shifted toward city halls. Mayors and governors are increasingly the ones holding the actual purchase order. When buyers and builders meet in person, the time between concept and pilot collapses. SusHi Tech's structural innovation, in 2026, is to engineer that collision deliberately.
Professor Yoshimura's Framing — Top-Down or Bottom-Up
Professor Yoshimura opened with footage of trams being introduced in Barcelona at the start of the 20th century. Traffic rules at the time were unwritten, but citizens self-organized and produced flowing traffic without collisions. That, he said, is the original image of the "bottom-up smart city." On the other side, MIT Media Lab's autonomous traffic-light system was offered as the textbook "top-down smart city."
"Which kind of smart city are you aiming for?" — that question became the axis of the entire session. Rather than answering himself, Professor Yoshimura had each of the three city representatives articulate their own philosophy. What made the question excellent is that it forced the audience to realize that "city OS design is not a question of technology choice — it is a question of how you see the citizen."
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Seoul — 210,000 Cameras, and Standing Beside Seniors
Once Director General Kang Jeong-han took the stage, the numbers were overwhelming. The 210,000 AI cameras installed across Seoul are integrated into an "AI Safety Center", detecting fires, falls, and crime in real time around the clock. Once detected, an automated alert is sent to police and fire services.
Seoul also runs a "Digital Sex Crime Monitoring Service." AI detects illegal content automatically 24 hours a day, providing rapid takedown, counseling, legal aid, and psychological care in a single integrated flow. The initiative won the United Nations Public Service Award in 2024. What matters here is that the goal is the shortened recovery process for victims. Technology is the means; the social goal — "no one suffers in silence" — comes first.
What moved me most was the story of the "Digital Inclusive Plaza." It is a service that teaches seniors how to use digital tools, in person. The stance is consistent: "Take all the time you need. We do not leave anyone behind by the pace of technology." A frontier city operating AI through 210,000 cameras is also saying, "Slow is fine." That dual stance is, I think, the very essence of a "Human-Centered AI City."
Seoul is the capital of South Korea and a megacity that hosts roughly 20% of the country's population. Cities with high population density tend to function well as smart-city laboratories. Over the past decade, Seoul has continued to strengthen its "Smart Seoul" strategy, gradually building "digital infrastructure for citizen life" — public-transit cards (T-money), citizen participation platforms (mVoting), and IoT sensor networks (S-DoT). The 210,000-cameras headline tends to walk on its own, but a decade of institutional design sits beneath it.
Director General Kang's framing of governance also deserves attention. He drew an explicit line between "surveillance" and "safety," and made the point that the legitimacy of the AI Safety Center depends on transparent rules about who sees what data, for how long, and with which audit trail. Without that institutional layer, 210,000 cameras would simply be 210,000 lenses pointed at citizens. Seoul's choice to publish its data-handling policies and review them through an independent committee is what turns a surveillance grid into a public utility. That distinction is easy to miss when you are dazzled by the hardware count.
Barcelona — Data as a Tool for Dialogue with Citizens
Maria Bigas's presentation from Barcelona was full of urban planning professionalism. Barcelona has built a website that organizes data to answer the questions citizens face when buying or renting a home. It is not just open data. The data is structured to "support citizen decision-making."
The "Urban Atlas," developed over six years, was equally impressive. It compares current building regulations against actual building volumes and answers, with numbers, the question "How much more building can Barcelona stack?" When a city evolves through "densification" rather than expansion, this kind of analysis becomes decisively important.
She also described an 83-square-meter physical model used as a tool for dialogue with citizens. In the era of digital twins — and yet a physical model. I took that as the expression of a philosophy: "Data exists not to explain, but to enable dialogue." Standing in front of a physical model and arguing produces a kind of embodied conviction. That quality of consensus simply doesn't emerge from remote tools or dashboards alone.
The icing on the cake was the "Participatory Budget Process." Citizens propose directly, and votes determine budget allocation. Annual urban maintenance investment of more than 4 million euros is being optimized with data while simultaneously expanding citizens' decision-making power. Tokyo has plenty to learn from how these two wheels are kept turning together.
After regenerating itself through the 1992 Olympics, Barcelona became a global model city as a smart-city policy pioneer. But in 2018, then-mayor Ada Colau launched the slogan "Rebel Cities" and pivoted hard from "smart cities led by tech companies" to "digital cities where citizens hold sovereignty." The Urban Atlas and participatory budgeting sit on that line of policy reorientation. Barcelona is one of the cities that most quickly embodied the transition from the first to the second generation of smart cities.
The Superblock program, mentioned briefly during the Q&A, is another crucial piece of the picture. By restricting through-traffic across nine-block clusters and converting interior streets into pedestrian-priority space, Barcelona has reclaimed urban land for citizens. The point is not the physical redesign alone — it is that the program was negotiated street by street with residents, with measurable air quality and noise targets attached to each transition. The data infrastructure underneath (sensors, mobility models, before/after comparisons) supports public deliberation rather than replacing it. That is the Barcelona pattern: the algorithm sits underneath the conversation, never on top of it.
Tokyo — Society 5.0 and the KK Line Project
What Professor Deguchi from the University of Tokyo introduced was the KK Line (Tokyo Expressway) Rooftop Pedestrian Conversion Project. The roughly 2-kilometer structure, spanning 14 blocks, was completed in 1966 and stood as a symbol of postwar Tokyo's growth. In 2025 it ended its role as a vehicle expressway, and the rooftop will be reborn as pedestrian space across the 2030s and 2040s.
His explanation that LiDAR is being used to visualize and analyze pedestrian flows on this project was, to me, deeply suggestive. Reusing infrastructure and validating design with digital technology are progressing as one integrated project. This is not merely a smart city. It is the work of "designing new public space digitally" on top of the city's historical layer. It is an internationally calibrated effort comparable to New York's High Line or Paris's greening projects.
Professor Deguchi also referenced the concept of Society 5.0. Metropolitan-scale base-station data, station-area utilization analysis, pedestrian-level LiDAR — choosing the right data at each scale is, even now, one of the hardest design problems for me. I wrestled with it during my time on data strategy at Panasonic. Do you read the macro picture with coarse-resolution data, or chase individual optimization with fine-resolution data? Knowing which to use when is the heart of urban DX.
There is a second design challenge embedded in the KK Line project that I think will become a global reference: the question of how a city retires hard infrastructure gracefully. The expressway is not being torn down — it is being repurposed. Many of the world's cities will face similar decisions in the next twenty years as 1960s-era infrastructure reaches end of life simultaneously. Tokyo's bet on adaptive reuse, validated with digital pedestrian-flow modeling before construction begins, is a methodology other cities will study. The fact that the project will unfold across two decades also matters. Smart-city projects that promise dramatic results within a single mayor's term are usually the ones that fail. The KK Line's slow, generationally patient timeline is, in itself, a design choice worth respecting.
Author's Reflection — "Smart" Is Not the Quantity of Technology, but the Depth of Standing Beside Citizens
After listening to all three cities, the parting line Professor Yoshimura threw out hit hard.
"We have entered an era where the conventional trade-off between economic growth and environmental load (lower-left to upper-right) can be resolved through digital data and changes in human behavior. The carbon-neutral-era city moves from upper-right to upper-left — growing while reducing its load."
I was listening to that line layered on top of TIMEWELL's "democratization of challenge." Building infrastructure for challenge means raising the lever for someone to succeed. Building city infrastructure means raising the quality of life for someone. Structurally, they are the same.
What stood out is that neither Seoul nor Barcelona is competing on "the quantity of technology." Behind Seoul's 210,000 cameras is the commitment to "providing crime victims with 24-hour psychological care." Behind Barcelona's 83-square-meter physical model is "dialogue with citizens." Both are designed not from a technology starting point but from a citizen starting point.
Turning back to Tokyo. The KK Line project is a wonderful effort. But the "opportunities for citizens to participate in the design process" do not yet feel sufficient. Now that the G-NETS mayoral summit has begun, there is a lot to learn from Barcelona's participatory budget process. The next stage of Tokyo's smart city, I believe, begins by re-asking the question of "Who designs?"
The question of "Who designs?" applies not only to cities but to society's inclusion infrastructure itself. From the perspective of how to embed residents of diverse backgrounds in the city's decision-making process, this connects to the discussion in Foreign Resident Symbiosis Policy. And the context in which independent individuals build city communities ties directly into Studio STELLAR and the Era of Independent Talent.
Democratization of Information and Debate — Where Startups Can Step In
One more point I want to make from the perspective of the startup ecosystem. Behind Seoul's 210,000 cameras, behind Barcelona's Urban Atlas, and behind the KK Line LiDAR analysis, there are countless startup technologies underneath. The era of "one company supplying the city OS" is over; the era of "countless startups contributing as modules" has arrived.
This is an opportunity for Japanese startups. Cities connected through G-NETS are likely to become the "first customers" for startup technology, one after another. In fact, at the SusHi Tech venue, mayors and city administrators stopping by startup booths was a frequent sight. At TIMEWELL too, while we accompany "individuals who want to take on challenges" through partnerships with local governments and large corporations, there is still plenty of room to design the route by which city administrations can directly access startups.
What this requires from startups is a different kind of go-to-market discipline. Selling to a city is not selling to an enterprise. The buying cycle is longer, the procurement language is denser, and the political risk for the buyer is higher. Founders who treat city sales as "B2B with extra paperwork" tend to lose, while founders who treat the city as "a customer with citizens as the ultimate users" tend to land deals that compound. Building a small but real GovTech sales muscle — with people who can read public-sector RFPs and negotiate with risk-averse procurement officers — is, in my reading, one of the highest-leverage investments a Japanese deep-tech startup can make right now.
In Closing — Three Requirements for Next-Generation Smart Cities
The "three requirements for next-generation smart cities" I took home from the entire session are these. First, data design that expands citizens' decision-making power (the Barcelona model). Second, inclusive technology rollout that leaves zero citizens behind (the Seoul model). Third, gradual digitalization that respects the city's historical layers (the Tokyo KK Line model).
Not the quantity of technology, but the depth of standing beside citizens. The smart city competition has entered its next phase. Whether Tokyo, as the hub of G-NETS, can set the new standard for this "stand-beside-citizens-style smart city" — there, the future of Japan's startup ecosystem and the next form of the "infrastructure for challenge" we at TIMEWELL build, are overlapping.
If I had to name one practical takeaway for Japanese executives sitting in the audience, it would be this: stop benchmarking your DX initiatives against other Japanese companies. Benchmark against cities. Cities like Seoul and Barcelona have to design for adversarial users, edge cases, and the most vulnerable stakeholder simultaneously — children, seniors, people with disabilities, recent migrants, victims of crime. The level of robustness and humanity demanded by city deployments forces a kind of design rigor that most enterprise DX projects never have to face. If your AI rollout cannot stand up to a city's quality bar, it almost certainly will not stand up to long-term consumer trust either. The smart-city frontier is the most demanding training ground for AI products, and Japanese companies that lean into that difficulty will come out with more durable products on the other side.
Connecting This to Your Corporate Strategy and New Business
If you want to translate these policy moves and urban implementation discussions into your own corporate strategy, new business, or AI rollout, TIMEWELL's AI consulting service WARP takes individual inquiries. BtoG business development with smart city / GovTech as the entry point, product design for human-centered AI, and building touchpoints with local governments and G-NETS member cities — you can start with a 30-minute online consultation.
Related Articles
- SusHi Tech Tokyo 2026 Keynote Report | Governor Koike and Prime Minister Takaichi on the Seriousness of Building a "Startup Nation Japan"
- Studio STELLAR and the Era of Independent Talent
- Foreign Resident Symbiosis Policy
References
[^1]: YouTube. "Smart Cities Evolving for Citizens: Creating the Future Together with Leading Cities." https://www.youtube.com/watch?v=kK-y7VX9tFc [^2]: SusHi Tech Tokyo 2026 Official Site. https://sushitech-startup.metro.tokyo.lg.jp/ [^3]: Tokyo Metropolitan Government. "About the G-NETS Mayoral Summit." https://www.metro.tokyo.lg.jp/