You can pass Osento for years and not even realize it's there. Located in a Victorian house on Valencia with no sign in front when it's not open, you have to know about it to find it. For women who enjoy a homespun alternative to the fancy bathhouses of the Kabuki, Osento is the city's best-kept secret. Inside is a homey little bathhouse, complete with hot tub, two tiny outdoor saunas, and a cold soaking pool. Women clients (no men allowed) can store their things in a locker and soak as long as they want. There's even a "quiet room" with bunk beds, where you can nap, and a kitchenette where lemon-flavored ice water is always available. On a recent afternoon, a group of women relaxed here after a hard day of anti-war protesting downtown. But you don't need to have blockaded traffic during rush hour to treat yourself at Osento. At only $10 to $15 (sliding scale) per session, you can justify soaking on a whim any old time.