Green Plaza Shinjuku Capsule Hotel is one of the biggest capsule hotels in Japan, with 593 capsules (enclosed bunks) for men only -- although there is a separate women's section made up of 30 bunk beds in a dormitory setting, as well as an on-site beauty parlor and sauna. The men's section has an attached bathhouse, spa, and sauna. Some past guests are put off by the communal bathing facilities and the abundance of rules enforced by the management, which give the hotel an institutional feel. For example, guests can't leave the premises after check-in without requesting a pass. Travelers keen on trying the capsule experience might also want to consider the nearby Shinjuku Kuyakushomae Capsule Hotel, which is smaller, immaculately clean, and seems to have a more relaxed atmosphere.