Located in Adachi-ku, Tokyo, 'Natural Hot Spring Myojin-no-Yu' is a genuine natural hot spring facility featuring a rich and heavy sodium-chloride strong saline spring. The brownish strong saline spring, pumped from deep underground, fills the open-air bath, and the mineral aroma rising from the surface evokes the atmosphere of a hot spring area. The salt enveloping the skin retains body heat, and even after leaving the bath, the warmth continues to radiate from within, making it a 'hot water' bath. The sauna offers a dry sauna at approximately 90°C and a mist sauna using steam from the natural spring. The automatic löyly, activated every 20 minutes, weaves heat into the air, while the gentle spring mist envelops and warms the body deeply. Cooling down is achieved with a rock bath-style cold plunge bath set at about 14°C, providing a sharp contrast of hot and cold when returning to the strong saline spring.