In Tomioka City, Gunma Prefecture, a young sericulture farmer is producing high-quality cocoons by utilizing the second floor of an old traditional home and a plastic greenhouse. He once majored in agricultural economics at university, planning to support agriculture from the sidelines as a civil servant. So why did he decide to step onto the front lines and become a key player in the dwindling sericulture industry?

We sat down with Hiroo Asai from the Daimaruya Sericulture Experience and Training Center to discuss his techniques for raising silkworms using all five senses and his vision for building a sustainable farming model for the next generation.

From Supporter to Player: Captivated by the Hands-On Nature of the Work

In college, Asai majored in agricultural economics with the goal of becoming a civil servant who supported agriculture from behind the scenes in a government agency. But as he visited farms abroad, he found himself drawn to the practical wisdom and physical intuition of the farmers—knowledge that could never be captured in a textbook.

"While interacting with farmers overseas, I developed a desire to absorb the kind of knowledge you can only gain in the field—things like, 'You plant this crop when that flower blooms,' or understanding how a particular piece of land behaves. That's what led me to apply for the Japan Overseas Cooperation Volunteers."

After returning to Japan from his time promoting mushroom cultivation in Nepal, Asai met Kanai, a sericulture farmer in Tomioka. Asai was deeply inspired by Kanai's fluid, efficient movements and the way he used all five senses to raise his silkworms. It was then that he decided to step into the world of sericulture himself, not as a supporter, but as a hands-on player.

Decoding Silkworm Growth with the Five Senses in a Dialogue with Nature

Much of the work in sericulture involves harvesting mulberry leaves to feed the silkworms. At the same time, the process demands meticulous environmental control tailored to each stage of the silkworms' development. Asai skillfully manages temperature and humidity by alternating between the second floor of his traditional home and a plastic greenhouse.

"A silkworm's growth rate is dictated by temperature. If it gets too warm, they start spinning their cocoons too soon," Asai explains. "You have to synchronize the development of silkworms that are growing at different paces, and that’s where using all five senses to make a judgment call becomes critical."

Just before the silkworms are ready to spin, a faint ammonia-like scent fills the rearing room, and their bodies shift in color from white to a pale yellow. While Asai keeps records of these subtle daily shifts, he ultimately trusts his own eyes and intuition for the final call. Even in our modern, data-driven age, a sharp observational eye is indispensable when your work involves caring for living creatures.

Pioneering Quality-Driven Branding and Sustainable Farming with Leeks

Today, the Tomioka Silk Promotion Organization purchases the entire cocoon harvest within the city, managing everything from production to sales. Usui Seishi, a silk reeler in Annaka City, has even implemented a bonus system for top-tier cocoons, championing a business model where quality is king. One standout success is "プラチナボーイ," a male-only silkworm variety yielding incredibly fine thread, which has earned rave reviews from high-end kimono boutiques in Ginza.

"A shift is happening toward prices that can actually sustain a livelihood. But of course, to justify those prices, you have to deliver on quality. We used to think that the more you produced, the better off you were. Now, we're seeing a new model emerge: focus on quality, produce a moderate amount, and you can still earn a very comfortable income."

This dedication to quality extends to how he integrates other crops. Asai cleverly uses the abundant silkworm droppings as rich compost to grow Shimonita leeks during the winter. This smart combination of summer silkworm farming and winter leek cultivation creates a stable, year-round source of income.

The sericulture industry faces daunting challenges. In Tomioka, the average farmer is over 75 years old, and the tools of the trade are no longer being manufactured. Despite these hurdles, Asai is actively networking with local farmers, searching for ways to build a support system that helps newcomers find their footing and stay in the business.

While barriers like initial investment and finding suitable space are real, he is working to position sericulture as a viable business option for farmers, leveraging government aid and creatively using abandoned homes. By blending the time-honored techniques and wisdom of the past with a sharp, modern business acumen, Asai's pioneering work is illuminating a new path forward for Japan's sericulture industry.