Japanese master architect Kisho Kurokawa designed Capsule hotel in 1979, and Kotobuki Seating Co., Ltd. commercialized the sleep capsule as a product. In 2020, his disciple, Suzuki, and Kotobuki developed Cardboard Sleep Capsule for refugee people of earthquakes or disasters under covid 19 circumstances. Connected two returnable boxes for shipping form a single room, with holes as an entrance and a window for daylighting and ventilation. It consists of the room, stair, outer private space with a desk and a chair. A two-story building accommodates many people while keeping social distancing.