Kojika-no-Yu is a day-trip hot spring facility located in Yumoto, Nasu-machi, Nasu-gun, Tochigi Prefecture. Situated along the main street of Nasu Yumoto Onsen district, it uses the same source spring as the famous "Shika-no-Yu" (Deer Hot Spring), which has approximately 1,300 years of history. Opened in 2006, this relatively new facility was originally renovated from the bathhouse of the historic ryokan "Tachibana-ya Hanaya Hotel" to make it more accessible for day-trip visitors. It currently operates exclusively as a day-trip facility.

The hot spring is an acidic sulfur-containing calcium sulfate spring, characterized by beautiful milky white sulfur waters. Like Shika-no-Yu, it emits a strong sulfur odor and has a smooth texture, though users may feel that oils are drawn from their skin after bathing. The spring is highly therapeutic, believed to be effective for neuralgia, muscle pain, joint pain, skin conditions, and gynecological ailments.

The facility features indoor baths (medium and high temperature) and outdoor baths, with shower facilities and washing areas where visitors can wash their bodies and hair - a significant advantage over Shika-no-Yu. The men's outdoor bath is made of wood, while the women's outdoor bath is made of ceramic. Operating hours extend until 9 PM (compared to Shika-no-Yu's 6 PM closure), making it convenient for post-sightseeing visits.