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A Single Thread to Save Okinawa's Sugarcane Fields: The Circular Economy Vision of SHIMA DENIM WORKS

2026.05.07

In Okinawa Prefecture, one company is developing a new sustainable material by utilizing "bagasse," a byproduct of the region's key crop, sugarcane. That company is SHIMA DENIM WORKS. Its founder, Naoto Yamamoto, launched the business with a mission to protect Okinawa's iconic landscape and revitalize local industry.

We spoke with him about the mission woven into every piece of denim—a challenge to build a circular economy that brings together regional revitalization and Japanese manufacturing expertise.

PROFILE

Naoto Yamamoto

After graduating from university, he joined an advertising agency involved in regional revitalization projects across Japan, where he handled project planning, product development, and branding.

In 2018, he struck out on his own and founded R-innovation Inc., a company dedicated to regional revitalization through the upcycling of underutilized resources.

In October of the same year, he launched "SHIMA DENIM WORKS" to sell products made by upcycling "bagasse," the fibrous residue from sugarcane.

In 2021, he established Curelabo Inc. to focus on the R&D, manufacturing, and sale of sustainable materials.

He is now scaling the business, expanding this Okinawa-born business model both domestically and internationally, and currently upcycles approximately 30 types of residues from 21 locations across Japan.

The Decline of Sugarcane Fields in the Shadow of Tourism

Over the past 20 years, Okinawa Prefecture's tourism industry has boomed, now welcoming around 10 million visitors annually. However, this success has come at a cost. With limited resources funneled into tourism, the region's primary industries have felt the strain. The sugarcane industry, a key crop covering half of Okinawa's arable land, is facing decline due to labor shortages and other factors, leading to the consolidation of sugar mills on the main island.

Sugarcane is more than just the source of sugar; it's one of the world's most-produced crops and plays a vital role in absorbing significant amounts of carbon dioxide. In Okinawa, its importance extends to environmental conservation, as it helps prevent red soil runoff into the ocean, thereby protecting precious coral reefs.

Having spent 17 years at a tourism-focused advertising agency working on local economic revitalization, Yamamoto confronted this structural challenge firsthand: the decline of primary industries in the wake of tourism's growth. He realized that for a sustainable community to thrive, tourism and the natural environment must coexist. This conviction led him to start developing a business plan aimed at protecting Okinawa's iconic sugarcane fields.

Giving Value to Bagasse

The process of refining sugar from sugarcane generates large quantities of byproducts, including molasses and a fibrous pulp from the stalk called "bagasse." While some bagasse is thermally recycled as fuel for the mills' boilers or used as compost on farms, a chronic problem has been the massive surplus that goes unused.

'Bagasse,' the fibrous residue from sugarcane

As a fuel, its value is only about 26.5 yen per kilogram, and as compost, a mere 1.5 yen. This presents a challenge, as its economic added value is extremely low. Considering the energy costs for transportation and processing, existing recycling methods alone won't directly boost the sugarcane industry's profitability.

This led Yamamoto to devise an upcycling system to add significant value to this bagasse, aiming to rebrand the entire sugarcane industry. Focusing on the fact that the apparel industry has the second-largest environmental impact after the oil industry, he embarked on a new venture in the realm of "clothing"—one of life's essentials—to develop a new fiber from bagasse.

Mixed-Fiber Papermaking and Paper Yarn Production

The unprecedented challenge of creating fiber from bagasse was a long and difficult road. Yamamoto focused on cellulose (dietary fiber), the main component of bagasse, and turned his attention to traditional Japanese washi paper manufacturing techniques.

He explored a papermaking technique known as "konsho" (mixed-fiber papermaking), which involves blending the powder of dried and crushed bagasse with the long fibers of Manila hemp, a traditional paper material.

However, the path was far from smooth. Finding a factory willing to collaborate on the development proved to be exceptionally difficult. Machines capable of producing thin paper are scarce in Japan, and major corporations reportedly demanded high development fees or set unrealistic conditions for large-volume production.

Nevertheless, he eventually secured a partnership with a paper mill through the help of many people.

From a technical standpoint, maintaining the strength of "konshoshi" (mixed-fiber paper), which combines two different plant materials, is challenging. Increasing the bagasse content enhances its environmental significance, but it severely compromises the paper's strength. After repeated physical property tests during the slitting and twisting processes, as well as checks on the texture during weaving and knitting, it was determined that the optimal bagasse content for stable quality is around 20-30%.

The "bagasse paper" created by combining bagasse and Manila hemp

A New Functional Fiber: Absorbent, Quick-Drying, Deodorizing, and Antibacterial

The result is a bagasse-derived paper yarn with unique properties not found in conventional textiles. Its most remarkable feature is its lightness—less than half the weight of cotton. Additionally, the porous structure of the paper raw material provides excellent water absorption and quick-drying capabilities.

Furthermore, tests have confirmed its high deodorizing and antibacterial properties, revealing its potential as a functional fiber. The polyphenols in bagasse appear to contribute to these functions.

"SHIMA DENIM" is the final product, woven in collaboration with a weaver in Fukuyama City, Hiroshima Prefecture—a region famous for its denim production. This special yarn is used for the weft, while cotton is used for the warp.

Enjoy the unique aging of the denim, which highlights the texture of bagasse and Manila hemp

Initially, the jeans have a crispness and stiffness characteristic of paper, but with wear, they absorb moisture, soften, and mold to the wearer's body.

The aging process of the denim is also unique. Since the weft threads visible on the reverse side are not pure white but a natural light brown from the bagasse, the denim develops a deep, vintage-like character that sets it apart from ordinary denim as it fades.

A Circular Supply Chain Expanding from Okinawa to All of Japan

What's also notable is that SHIMA DENIM WORKS' initiatives are not limited to Okinawa. Starting from Okinawa, Yamamoto aims to build an "All-Japan" supply chain by collaborating with businesses across the country that possess outstanding manufacturing technologies. His goal is to contribute to regional revitalization across the country by partnering with local industries in Japan—many of which are in decline due to competition from cheap overseas products—to create high-quality products at fair prices.

These efforts are expanding to include unused resources other than sugarcane.

In Fukuyama City, Hiroshima Prefecture, the company developed "denim born from roses" by creating yarn from the pruned branches of the city's official flower. In Yamagata Prefecture, they are producing knitwear from pruned cherry tree branches and "cherry notebooks" for new elementary school students.

The ripple effect of SHIMA DENIM's technology has led to a series of collaborations with other companies

What's more, through collaborations with major corporations, new initiatives are constantly emerging to upcycle business byproducts. These include using malt feed from Sapporo Breweries, stems and leaves from hop harvests, cacao husks from Meiji's chocolate production, and even broken bats from professional baseball players under contract with Mizuno.

Crafting a Future Landscape with a Circular Economy

The journey for SHIMA DENIM WORKS has only just begun. With a long-term perspective, Yamamoto envisions establishing the textile industry as a new secondary sector firmly rooted in Okinawa.

He explained that he hopes to contribute to genuine regional revitalization by bringing the raw material processing and yarn-spinning stages—currently dependent on facilities outside the prefecture—to Okinawa, thereby creating new employment opportunities.

Utilizing waste materials enables the production of diverse yarns across various regions.

Simultaneously, their gaze is turning toward the international stage. They are actively participating in trade shows in environmentally conscious Europe, where their products are gaining significant attention as an ethical material born from Japanese technology. The plan is to build a sustainable economic foundation by establishing sales channels not only in Japan but also overseas.

Looking ahead, they are also considering expanding the business model established in Okinawa to other major sugarcane-producing nations around the world, such as Thailand.

This story, which started with a single piece of denim, is now working to protect Okinawa's pristine landscape and preserve Japan's manufacturing heritage. It is poised to create a powerful movement that will ultimately contribute to a global circular society.