Hanazono Room

Hanazono Room, officially No. 136 Hanazono Room, is an apartment room with an indoor swimming pool located in the uppermost floor of the Sun Mall Crest Condominium in Shinjuku district in Tokyo, Japan. Operated by P-Studio, the indoor swimming pool in the apartment unit was a venue for many Japanese pornographic skits with themes of swimming and poolside intercourse. With its association with Japanese pornography, the indoor pool inside Hanazono Room became popularly known as That Pool in internet subculture.

Source: Wikipedia