Spa World

Take the subway, either the Midosuji Line (red on the subway map) or the Sakaisuji Line (brown) and get off at Doubutsuen-mae Station (M22 & K19). Take the exit that indicates Spa World (clearly written in English). Once you're at the top of the escalators (at street level) there will be a convenience store on your right and stairs to your left. Take the stairs up through the fun park until you reach the entrance of Spa World.

It's open 24 hours but the best times are on weekdays between early evening (5-6pm) and midnight (before the last train) when locals finish work and come to cruise.

The crusiest spots in the Asian zone are the salt sauna, the wet sauna next to the Islamic spa right by the entrance, and the mist sauna in the far corner of the complex behind the Balinese massage room. The spas and saunas themselves aren't suitable for action. Just show off your (you'll know who's interested as they'll be showing theirs off too) and then head over to the toilets to complete your mission. Use the cubicle the furthest from the entrance. Japanese guys are particularly curious about foreigners and will usually be straight-forward and direct about going after what they want.

Nudity: As in all Japanese saunas and bath houses nudity is essential and swimwear is strictly prohibited (except on the roof tope pool). Wrap the koshimaki (small loin towel) that you're given on entry around your waist. Have only in the toilets (they're sparkling clean to comply with Japanese hygiene standards).