Mikokuyu 御谷湯 is stylish Japanese bathhouse with contemporary trappings. Ease into one of their natural hot spring baths to relieve some stress and soothe muscles sore from walking all over Ryogoku. Of particular note is the all-natural, coffee-colored black baths, which have been headliners of Mikokuyu since its opening.
Entrance is 460 yen, with rental towels costing another 30 yen, but you can simply show up as you are, no preparation needed. Tattoos are allowed, and foreign clientele often visits.
Being able to see Skytree while soaking in the warm water is a special treat.