Japan's volcanic terrain means there's no shortage of natural hot springs, called onsen in Japanese. Onsen are not only great for relaxation (especially during winter!), but claim to provide other health benefits too. Here are some tips for first-timers: 

• Onsen are generally gender separated, often with a red curtain for women and blue curtain for men. 
• When entering the onsen, there will be a change room with baskets shelves or lockers to store your clothes and other items. Undress here and remember: no swimmers and only take a small towel (often but not always provided) with you into the shower/bathing area.  
• The first thing you'll see is the shower/bathing area. Sit on a stool and clean yourself from top to toe, ensuring all soap/shampoo has been rinsed off.  Now head to the baths. If you have long hair, it's better if it's tied up so it doesn't go in the water. Look for the rotenburo (outdoor bath) as they often have great views (most but not all places have one). It can feel a bit funny going outside completely nude, but it's worth it!
• Keep your small towel to the side, out of the water. You can even place it on your head if you like.