A Light Truck Wooden-box Connecting Satoyama to Urban in Ehime, Japan

The Moving Wooden Circle
WA(わ) of moving wood link of moving wood, cycle of moving wood, relationship of moving wood.
(WA(わ): Ring(輪), Circle（環）, Harmony(和))

A wooden crate mounted on a light truck connects cities and mountains

photo by studio colife3 Workshop scene amidst autumn-colored mountains.

The client is a local company based in Uchiko Town, Ehime Prefecture, operating under the philosophy of “uncut forestry” and creating gateways to mountain forests.

Their mission is to revitalize regional forestry by developing a mobile work space capable of fulfilling the following functions.

1. Exhibition and workshop space for promoting products that revalue underutilized mountain resources and outdated wood resources.

2. Classrooms for programming education and renewable energy education through forestry practices.

The unutilized forest resources they focus on range from various wood materials generated throughout the forestry management process-from tree felling to sawmilling-spanning not only coniferous species but also broadleaf trees and shrubs.

Their approach features an innovative perspective on mountain resources that includes applications beyond construction materials, such as fragrances and other value-added products.

What emerges from this is the evolution of society’s relationship with mountains over time-a transformation that aligns with contemporary movements toward decarbonization, renewable energy, and natural ecological cycles.

Table of Contents

Light Trucks and Satoyama

The client initially proposed using a light truck as the primary vehicle for mobility.

One key reason was to eventually develop these units as mobile shops and homes for local loggers, farmers, and outdoor enthusiasts.

Using standard light trucks-commonly employed in rural Satoyama areas offers the advantage of updating Satoyama functions by introducing new elements into the local landscape.

The load capacity for the light truck has strict limitations: 2.5 meters in height above ground level, a maximum width of 1.48 meters (the standard for light vehicles), and a payload capacity of 350 kg.

The basic structure employs locally sourced high-density sugi (Japanese cedar) construction-grade lumber as the core framework, reinforced with structural plywood panels.

This semi-monocoque design features L-shaped plywood inserts at the shorter edges for rigid bonding, achieving a balance between weight reduction and structural integrity while enhancing customizability for vertical openings.

The transportable boxes are designed to be easily attached and detached from the light truck, allowing a single vehicle to serve dual purposes-both for rural agricultural work and urban-based activities in the countryside.

The loading/unloading mechanism utilizes the space between the light truck’s side panels and cargo bed, secured with simple metal fittings – allowing even women to attach/detach the box without requiring complex bolting procedures.

By using standard construction-grade single-layer steel pipes for loading and unloading, we kept costs down while utilizing materials that are readily available and commonly used in rural mountain areas as part of daily life.

The rural work truck – the backbone of mountain communities – drives toward town carrying wooden boxes from the countryside.

Heartwood and the Tree

When considering their diverse activities involving various types and parts of wood, we asked ourselves what might serve as their core principle. During our research, the term “heartwood” emerged as particularly significant.

Heartwood refers to the central, darker-stained portion of a tree’s trunk, contrasting with the lighter sapwood.

The tree’s trunk grows outward through a layer called the cambium, which continuously divides cells both inward and outward. Initially, cells form toward the interior as sapwood.

Over time, this transitional sapwood near the boundary between sapwood and heartwood undergoes chemical changes, eventually transforming into true heartwood.

The differences between wood species are more pronounced in the heartwood than in the sapwood.

Takeda Forestry's fragrance production using materials from mountain forests. — Takeda Forestry’s fragrance production using materials from mountain forests.

Heartwood and Fragrance

This heartwood-the dense, dark inner portion of the tree-contains the essential characteristics that define each wood species, including its natural preservative properties.

It’s precisely this heartwood that allows trees to grow to tremendous sizes while maintaining their vital functions, by serving as the structural core that sustains their growth.

As sapwood transforms into heartwood, it ceases metabolic activity while serving as the structural core that supports the tree’s growth.

This transformation enables the tree to continue expanding without losing its vital core, with enhanced preservative properties protecting this critical structural element.

Relationship between tree knots and pruning

While green leaves’ photosynthesis plays a vital role in a tree’s carbon sequestration, the red heartwood serves an equally important function.

In traditional Japanese homes where tatami rooms were the norm, it was common to decorate the ceiling with cypress planks featuring natural red heartwood without knots.

However, this practice has largely fallen out of favor today, with such materials now often mixed in with standard construction lumber.

Among the large- diameter timber carefully cultivated by local lumber farmers, there’s an increasing proportion of red-heartwood sections with perfect knots-free quality.

However, determining how to properly value these high-quality red- heartwood materials presents a significant challenge for forestry operations.

Takeda Forestry has established a system at local sawmills to sort and select high-quality red-heart sugi lumber, creating new opportunities for this premium material to gain visibility in the market.

For Takeda Forestry, hinoki cypress is another essential material in their operations.

The exterior's hinoki cypress presents a warm, human-like texture that contrasts sharply with the reddish- brown interior sugi wood. — The exterior’s hinoki cypress presents a warm, human-like texture that contrasts sharply with the reddish- brown interior sugi wood.

Cypress trees that tell the story of our founder

The founder’s grandfather was a lumberjack who specialized in harvesting four-sided knot-free cypress columns, passing down this legacy when he established the company. Today, they develop fragrances and deodorizing sprays using cypress extracts.

We decided to use this sugi heartwood with perfect grain as the primary structural element, accentuating its red hue by contrasting it with the hinoki cypress used for the outer perimeter.

The Oda area in Uchiko Town was once primarily a natural broadleaf forest region focused on timber production.

Even today, these broadleaf forests remain as beautiful autumn foliage spots in the deep mountains known as Oda Miyama.

Hardwood timbers represent another type of locally abundant yet underutilized resource, similar to sugi red heartwood that currently remains idle in the region.

The frame was made from cherry wood, chosen for its color similarity to the sugi red heartwood. The workshop table top features zelkova, while the outer paneling that contacts the wooden crates uses chestnut wood as a protective bumper.

Different wood species were carefully selected based on function, allowing visitors to experience the distinct characteristics of each material.

Interior space made of red cedar heartwood

A fragrance and scenery filling one and a half-tatami- sized space

The interior of the wooden box measures approximately 1.1m wide x 1.7m deep x 1.5m high a compact yet intimate space.

The interior features unblemished sugi red heartwood for both the floor and walls, creating an immersive experience of sugi’s distinctive grain patterns and aroma.

The ceiling uses standard hinoki cypress planks originally intended for wall rendering, carefully cut into narrow strips for the ceiling.

This product represents a new utilization method by Takeda Forestry, addressing declining use due to decreasing demand for traditional plastering and wet construction methods, as well as the widespread adoption of plywood.

The whiteness of hinoki whitewood contrasts beautifully with the reddish hue of sugi heartwood.

photo Takeda Forestry - Fragrance production process (Cromoji drying, Cromoli branches before distillation, Cromoli distillation) — photo Takeda Forestry – Fragrance production process (Cromoji drying, Cromoli branches before distillation, Cromoli distillation)

Fragrant Kuromoji lattice window

The upper skylights feature Kuromoji shrubs native to Oda’s mountains arranged in a latticed window style These shrubs, known for their strong aroma, were historically used in Shinto rituals.

Over time, they became employed in tea ceremony practices as toothpicks and hedge plants.

By developing fragrance products from this previously underutilized shrub, Takeda Forestry has created a new revenue stream for local lumber producers, encouraging them to maintain their forests through regular tree pruning while strengthening connections between rural mountain communities and urban areas.

Natural Cycles | Renewable Energy Education Workshops

Uchiko Town has established a decarbonization strategy and is actively promoting renewable energy utilization, particularly biomass power generation.

This mobile wooden box will also be used for educational outreach to promote renewable energy adoption. The roof features solar panels that generate power during transportation, with energy stored in battery compartments mounted above the driver’s seat.

The stored energy powers lighting systems during renewable energy workshops and provides electricity for drones and robots, allowing participants to learn about the relationship between renewable energy, daily life, and the forestry industry.

During workshops and promotional events, the wooden box is equipped with a retractable tarpaulin roof, creating an expanded under-roof space where portable modular furniture can be set up beneath the canopy.

The cover can be easily attached or removed using simple twist fasteners. The design incorporates clever space-saving features-for example, the tabletop serves as the door for the battery box-to minimize setup time.

Local wooden walls that are in line with natural cycles

Equally important as understanding how resources are created within natural cycles is learning how to use them effectively. Wood serves as an exceptionally tangible and relatable teaching material in this context.

Trees take decades to decompose after reaching the end of their lives in the mountains. We must therefore use wood resources even more gradually than this natural process.

The wooden box features armor-clad paneling on one side to enhance weather resistance against wind and rain, while allowing easy comparison of different construction methods. This technique is also traditionally used for exterior walls in Kura-warehouses in the Oda area.

Aiming for a new connection between Satoyama and the city

Japan’s forestry industry, dating back to the Edo period, has continuously pursued world-class sustainable approaches to mountain management through systematic tree planting.

However, after the period of rapid economic growth, Japan became increasingly dependent on imported timber resources.

This trend extends beyond forestry alone, as the connection between production areas (mountains) and consumption centers (cities) has gradually weakened.

Meanwhile, as society and environment have changed, so too have the needs and functions that mountains require from cities-and vice versa. It’s time to reexamine this mutual relationship.

-simply waiting in the mountains won’t make anything happen. A light truck – the backbone of rural communities – hauls wooden crates filled with mountain resources toward town.

To keep this “moving wooden circle” in motion.