Tajima Yahei (1822–1898) grew up in Shimamura, a village in Gunma Prefecture where many families practiced sericulture. Silkworms were hard to breed due to their delicate nature, and thus cocoons were hard to produce in great volume. When Yahei was a child, the silkworm farmers of Shimamura had to buy their eggs from Fukushima to the north. Yahei therefore dedicated himself to finding better sericulture techniques, and eventually discovered the importance of good ventilation. He called his technique seiryo-iku (literally, “chilled cultivation”) and wrote a book titled Yosan Shinron (New Theory of Sericulture) detailing his methods. This book was unique for including many pictures and diagrams that allowed even illiterate farmers to reproduce his techniques. Previously, only the people who lived in the colder and drier northern regions of Japan had been able to raise silkworms with any consistency, but by employing proper ventilation techniques farmers in the warmer and more humid southern regions of Japan could join the silk industry. Yahei also cultivated a breed of silkworms that could survive and reproduce in his hometown of Shimamura. These were such important achievements that Yahei was invited to the imperial palace to teach the court his new method.