Interview about Wagon Remodeling Food Van, winner of the A' Social Design Award 2025
The Japanese stone roasted sweet potato food wagon has long been an important presence in Japan's winters, bringing warmth and gently illuminating the town as night falls. It was reimagined through a contemporary design approach. In Kyoto, where the cityscape features a rhythm of horizontal and vertical elements like lattice windows, it was designed to integrate diagonal elements, adopted for structural reasons, in a way that complements Kyoto's streets as the ground and forms a figure within it.
View detailed images, specifications, and award details on A' Design Award & Competition website.
View Design DetailsThe design began with a simple yet pressing issue: many mobile sweet potato wagons look similar, making differentiation difficult. The client already offered a quality product and service, but because sales happen after dusk, the wagon needed to be instantly legible from a distance—independent of any lighting attached to the vehicle itself. This led to the decision to revisit the entire visual language of the vehicle.Set within Kyoto—a city whose streetscapes are organized by a clear rhythm of horizontal and vertical lines, from traditional machiya lattices to contemporary façades—the design treats that orthogonal order as the backdrop. Against this “ground,” diagonal elements are introduced to quietly single out the wagon in the urban field. The result is heightened visibility without disturbing the streetscape, producing a clear figure–ground contrast.The diagonals also serve structural and spatial purposes: they stabilize the frame while allowing an expressive interior layout within a small footprint. In doing so, the design balances clarity, function, and identity—all within a compact, mobile format.
In Kyoto’s biting winters, the archetypal street scene is guided by gentle light—paper lanterns on carts and small andon in the alleys that don’t flood space so much as invite you forward. I wanted to capture that atmosphere without replicating old forms. Stone-roasted sweet-potato wagons have long been part of this season: a small winter joy you bring home to family, a moment that warms cold hands. The design set out to amplify that memory—treating illumination as a soft beacon rather than spectacle. Warm, low-glare light grazes frames and working surfaces, with controlled fall-off around them, so the wagon reads clearly after dusk yet remains calm and intimate up close.The diagonal elements grew from two linked intentions. First, a structural one: bracing a compact body while carving out a slightly expanded interior pocket where serving and conversation overlap. Second, an urban one: in a city whose streets are organized by horizontal and vertical order, the diagonals establish a clear figure–ground relationship that sets the wagon apart without shouting. Together, the quiet lighting and the oblique frame produce a legible silhouette at a distance and a welcoming presence at the curb—an everyday warmth shaped for Kyoto’s winter.
Budget set our tempo, but the work was fundamentally collective. The carpenters and waterproofing specialists were not contractors “below” design—they were team members, thinking and deciding with us. We prototyped, failed, adjusted, and tried again together. The result unfolded over four wagons, each one learning from the last.The first generation began under the tightest constraints, so we adopted a straightforward timber frame assembled by the team. That choice matched the moment: fast to realize, understandable on site, and appropriate even when we considered long-term upkeep. As the wagons went into service, field use revealed what held up and what needed rethinking; we folded those lessons into the next build.As resources and understanding grew, later iterations became clearer. By the fourth wagon we executed a full renewal, transitioning from timber to a steel frame to increase durability, precision, and daily robustness. In parallel, close work with the waterproofing specialists simplified the exterior strategy: keep the body calm and repairable, treat joints and openings with care, and let necessary lines read as part of the composition rather than decoration.Functionally, this collaboration produced drier, tougher, easier-to-service interiors; aesthetically, it clarified an economy of means—structure doing the speaking, light helping legibility, and the envelope remaining visually quiet. The project did not succeed because of a hierarchy; it progressed because each discipline contributed at the right moment, and each generation answered the previous one’s questions.
The series expanded primarily because the client’s business grew; more units were needed as operations scaled. None of the generations were “fixes” for failures—each was the best we could achieve at that moment. Yet as each wagon went into daily use, client feedback from real operations revealed what only field conditions can: where circulation hesitated, which access points slowed setup, and where maintenance really happened. We used those notes to turn 100 points into 101—streamlining service flow, refining the diagonal frame for bracing and interior clearance, and simplifying openings and panel handling.Insights also cross-pollinated from parallel projects—detailing, assembly sequencing, and finishing methods that proved robust elsewhere were adapted here. By the fourth build, with resources and expectations higher, we undertook a full renewal for durability and precision (including a transition from timber to steel for the primary frame). Throughout, there was no hierarchy—carpenters, waterproofing specialists, and designers worked as peers, prototyping and deciding together. The cumulative effect is clear: stronger daily robustness, faster setup and cleaning, a calmer, more legible silhouette in the city, and an internal workflow that simply feels better—shaped directly by what the client learned in use.
The compact footprint was not arbitrary—it was set by the real geometry of use: the stone-roasting machine, the fuel tank, and the necessary stock capacity. From there we worked backward to the smallest overall volume that could still support safe operation and an efficient service flow. Making it larger would have been easy; the challenge was to achieve maximum usable space with minimal members, so material costs stayed disciplined and assembly remained straightforward. The result is a clear, braced frame that reads light but works hard.These dimensions also align with Japan’s kei-truck format, allowing straightforward mounting and setup on that platform when required. In Kyoto’s tight urban grain, the small size helps the wagon sit with the streetscape rather than against it: it preserves long horizontal views, keeps corners and alleys clear, and allows queues to form parallel to façades without disrupting pedestrian flow. Operationally, the compact envelope keeps working reaches within a comfortable range and reduces unnecessary movement during service. In short, the dimensions are both a technical consequence and an urban strategy—right-sized for the work, and quietly compatible with the city.
There is no fixed “traditional form” for the sweet-potato wagon—its essentials were a pre-recorded vendor chant, a roasting machine, and sometimes a small roof. After dark the details drop away, which is partly why this field rarely drew designers. Our aim was not to costume the wagon in nostalgia, but to carry forward what people remember: a small radius of warmth, a brief exchange, something to take home.We looked to the presence of the andon or chōchin—not to imitate their shapes, which would only produce an imitation, but to quote their spirit: a modest beacon that guides rather than performs. That sensibility is translated through proportion and restraint, a clear silhouette, and light treated as atmosphere instead of spectacle. Within Kyoto’s orthogonal streetscape, the diagonal frame provides a precise counter-gesture: it makes the wagon legible without shouting, and at the same time braces the compact body and opens a workable interior pocket. In this way, tradition is preserved in the experience and attitude, while innovation appears in structure, composition, and clarity.
In Japan, the kei-truck is a uniquely standardized vehicle platform with broad popular appeal due to its extensibility and ease of customization. While it is widely used—primarily for transport and sometimes for mobile vending—its practical efficiency often takes precedence, which can narrow how people imagine what such a small platform could become. With the Wagon Remodeling Food Van, our aim is to extend the possibilities and role of the kei-truck itself: to remain compact, rational, and serviceable, yet offer a clearer public presence and a more intentional spatial experience.By treating the kei-truck not just as a transport solution but as a designable cultural platform, the project suggests a path for street food to persist and evolve in contemporary cities: easy to set up, appropriately scaled for dense streets, and capable of hosting small public rituals without resorting to nostalgic replicas. In this sense, the contribution is twofold—preservation of the everyday act of street vending in a viable present-tense format, and evolution of the base vehicle’s role from purely logistical to meaningfully civic.
Being mounted on a truck bed means the wagon is constantly subjected to vibration and external forces, so the structure had to be inherently resistant. We therefore organized the frame as a truss built from simple triangular geometry. The diagonals are not decorative—they complete load paths, increase stiffness, and help the body hold its shape under repeated movement. Starting from this structural necessity, the space that remained between the members naturally determined the interior pocket and openings, so form followed the working geometry.Visually, the same oblique lines give the wagon a clear, memorable silhouette within Kyoto’s horizontal–vertical streetscape. The angled members read immediately at street scale, creating identity without excess means. In that sense, the diagonals do double duty: they make the unit tougher in use and clearer in appearance—the wagon looks the way it works.
There’s a limit to what one person can see or think alone.Our collaborations don’t assign fixed roles or hierarchies; instead, different backgrounds bring different questions, and the work improves through that exchange. We prototype together, look closely, and keep adjusting until the decisions feel clear to everyone. For the Wagon Remodeling Food Van, that shared process turned ideas into working geometry, organized space in a straightforward way, and refined the presence on the street—outcomes that emerged from conversation rather than predefined functions.
Above all, I would start with observation.Every place has its own culture, scale, and expectations, and any design should respect that rather than impose an imported image. What matters is to listen carefully—to the city, to the people, and to the client’s needs—and search for a response that feels natural in that specific context.Balancing cultural respect with the practical requests of the client is always enjoyable for me. If those elements come together honestly, a new wagon could emerge that belongs to its environment—not as a copy of Kyoto, but as something that grows from its own streets and everyday rituals.
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