薬師温泉 is a hot spring town in Gunma, Japan. Officially the water is classed as chloride spring and sulfate spring.
Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
Clear water with a faintly bitter taste. Known for holding heat.
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.