Traditional Japanese bath houses or sento usually open around 4pm. If you fancy a soak before then, you will need to search out what is called a "super sento."
Larger and more up-market, drive-in super sento have replaced the smaller, family-run bath houses in places like Nagoya. Only really Kyoto among Japanese cities has a large number of smaller, more intimate sento.
A good example of a super sento is Ten no Yu up the hill to the left from the Ueda subway station on the Tsurumai Line. There is a spacious rotemburo (outside bath) and sun lounge for topping up the tan and Vitamin D level, two saunas, a massage parlor and jacuzzi.
An early morning soak and sauna is a great way to shake off any hangover and leave you feeling much happier about life.
Ten no Yu
Tenpaku-ku, Ueda 1-703
Tel: 052 807 1123
Admission 700 yen
Map of Ten no Yu
Yahoo Japan Auction Service
Tokyo Apartment Lease