The Karuizawa Boys' Nature House, completed in 1986, stands as a notable example of institutional architecture designed by Miwa Environmental Planning. Located in Karuizawa, Nagano Prefecture, this residential facility serves as an educational retreat for youth programs operated by Chiyoda Ward, Tokyo. The building exemplifies the thoughtful integration of natural surroundings with functional design, reflecting the environmental consciousness of the 1980s. Its architecture balances practical accommodation needs with sensitivity to the mountainous landscape, creating a harmonious space for nature-based learning and development. The facility represents an important typology in Japanese public architecture dedicated to youth education and environmental engagement.