Koshio’s place was great for us, we were 4, but would say that 3 is probably the maximum that would be comfortable to stay. The futons were quite thin, but we don’t have an issue with that (and is often the case in Japan). Koshio was lovely and replied quickly and accommodated our requests. His hospitality was great and we even went for breakfast together (thanks Koshio!). It is a traditional house in a suburb outside of the busyness of Tokyo. But really easy to take the subway into the city. A lovely Izakaya is near by (next to the family Mart) - definitely one to check out too.