Historic Japanese sake brewery launches eco-friendly Toko AIGAMO using solar-powered weeding robot

On March 21, 2025, Kojima Sohonten, a historic sake brewery based in Yonezawa, Yamagata Prefecture, released a new product called Toko AIGAMO. The launch marks a significant step in the company’s ongoing commitment to sustainability and coincides with Earth Day celebrations on April 22. Toko AIGAMO is brewed using pesticide-free Dewa Sansan rice cultivated with the help of the Aigamo Robo™, an autonomous weeding robot powered by solar energy.

Kojima Sohonten began using the Aigamo Robo™ in 2022 to support environmentally friendly rice farming. The robot mimics the traditional method of using ducks to weed rice paddies, helping to maintain biodiversity without relying on chemical herbicides. The rice used in Toko AIGAMO is grown without pesticides or chemical fertilizers and polished to 80%, preserving much of its original character. The resulting junmai sake features a mild aroma, smooth texture, and a balanced flavor profile that reflects the natural qualities of the rice and local terroir.

Founded in 1597, Kojima Sohonten has been producing sake for over four centuries. In 2020, the brewery transitioned to producing only junmai sake—sake made without added distilled alcohol—as part of its broader environmental strategy. This move has helped the company focus on ingredient-driven brewing and has led to increased recognition both domestically and internationally. In 2024, export volumes rose by 50% compared to pre-transition levels in 2019. That same year, the brewery won first place in the Junmai Daiginjo category at the International Wine Challenge (IWC), one of the most prestigious global competitions for sake.

The release of Toko AIGAMO is accompanied by a new Sustainability Brochure and Promotional Video that outline Kojima Sohonten’s environmental efforts. These include initiatives such as carbon-neutral brewing practices and smart agriculture techniques. The company has also received several awards for its sustainability work, including two honors at The Drinks Business Green Awards 2023 and an Excellence Award at Japan’s 7th EcoPro Awards.

Looking ahead, Kojima Sohonten plans to expand its presence in international markets that prioritize sustainability. One innovation aimed at reducing environmental impact is the Toko Fresh Sake Server—a refillable system that allows only the liquid to be replenished, eliminating the need to transport heavy glass bottles. This product has already drawn interest from partners in Northern Europe, where sustainable practices are widely embraced.

In addition to product development, Kojima Sohonten is investing in internal education around sustainability. This summer, all employees will participate in training focused on water conservation, including a visit to the headwaters of the Mogami River—the source of water used in their brewing process. The company aims to deepen its involvement in watershed protection as part of its long-term environmental goals.

Kojima Sohonten’s approach combines traditional craftsmanship with modern technology and environmental responsibility. With products like Toko AIGAMO and innovations such as the refillable sake server, the brewery continues to position itself as a leader in sustainable sake production while honoring its centuries-old heritage.