This historic famous hot spring is the oldest in the history of Yunokawa Onsen, and is said to have once helped Hijikata Toshizo heal his wounds during the Battle of Goryokaku. Today, very few inns remain where you can fully enjoy this water, which is why it is called the "phantom red bath." It emerges colorless and transparent, but when the iron content reacts with the air, it turns into a beautiful tea-brown color, known as red bath. Its weak salt spring composition warms the body deeply and helps prevent you from getting chilled afterward. From the top-floor observation open-air bath, you can enjoy a historic, romantic bathing experience while gazing out over the Tsugaru Strait and Hakodate's magnificent scenery.

A natural hot spring representative of Yunokawa Onsen, featuring clear water and a smooth texture. The large bath is located on the top floor, and the large windows across the entire facade offer a luxurious panoramic view of Mount Hakodate, Hakodate's cityscape, and the sparkling night lights. In the spacious bathtub, wrapped in the pleasant aroma of hinoki cypress, you can fully enjoy the gentle water that leaves your skin feeling moist and comfortable. The contrast between this and the red bath, creating the "red and white baths," is another luxury unique to Kaiyotei.