【Kai Beppu】Adult's Free Research "What is a Hot Spring?" Unraveling Beppu Onsen from Nature, History, and Science, Now Available

Kai Beppu, a hot spring ryokan located in Beppu Onsen, Oita Prefecture, will host an adult-oriented free research program titled "What is a Hot Spring?" from July 20 to August 31, 2026. Beppu Onsen, boasting the highest number of hot spring sources and discharge volume in Japan, features various spring qualities, as represented by "Beppu Hatto" (Eight Hot Springs of Beppu), with their differences attributed to diverse factors including topographical backgrounds. Beppu's hot springs are formed from rainwater that takes 50 years to emerge from the mountains. This plan offers a program where participants can learn about this history with explanations from a special guide, experience the mysteries of hot spring components through hot spring dyeing, and immerse themselves in Beppu's hot spring culture from various perspectives by bathing in community-rooted "Jimo-sen" (local hot springs).

Background

Beppu Onsen, where Kai Beppu is located, ranks first nationwide in both hot spring discharge volume and number of sources. As represented by "Beppu Hatto," it is a hot spring resort where 7 out of 10 types of spring qualities, such as simple hot springs and sulfur springs, can be enjoyed. It is believed that various factors, including topographical backgrounds, contribute to the existence of such diverse spring qualities in a close area (*1). Furthermore, with over 100 communal hot springs known as "Jimo-sen" (*2), hot springs are deeply rooted in daily life. This program is designed not just for bathing, but to satisfy intellectual curiosity and offer a new way to enjoy hot springs, exploring why there is such a rich variety of spring qualities and why they are so deeply intertwined with daily life, in a manner befitting a hot spring resort. This plan was developed as a free research project that adults, not just children, can enjoy during the summer vacation season.

*1 Beppu City Hot Spring Data

*2 Beppu Hatto Onsen-do Official Website

Feature 1: Learn with a Special Guide. Unraveling the 50-Year Story from Rainwater to Hot Spring

Before staying, guests can experience the depths of hot springs at the Kannawa Onsen "Jigoku Onsen Museum." They will learn about the 50-year process of rainwater transforming into hot springs and the roots of Beppu's diverse spring qualities. As a plan-exclusive benefit, a special guide focused on the "50-year journey" and the spring qualities of "Kai Beppu" has been prepared. With a half-century of history as a backdrop, this is the beginning of a profound journey to savor the upcoming hot springs with all five senses.

Feature 2: A Drop of Hot Spring Changes Color. Experiencing the "Mysteries of Hot Springs" at Kai Beppu

At Kai Beppu, guests can experience "hot spring dyeing" supervised by Mr. Tomohiko Yukihashi of the Hot Spring Dyeing Research Institute. This dyeing method, where colors are fixed by adding hot spring water to natural dyes, is truly an experimental site to feel the chemical reactions of hot spring components firsthand. Guests will unravel the mysteries of hot springs with their eyes and hands, observing differences in color development due to the properties of hot spring water and color changes using "myoban" (alum), which is also the origin of the name Myoban Onsen. The completed work can be taken home as a travel memory.

Feature 3: Experiencing the Unraveled Secrets Firsthand with a "Jimo-sen" Tour

The next stage after unraveling the secrets of hot springs is the community-rooted "Jimo-sen." Over 100 communal hot springs, indispensable to the daily lives of Beppu citizens, breathe with unique local culture and etiquette. In this program, participants will learn the customs for comfortable bathing and actually experience bathing in the tubs. While experiencing the characteristics and effects of different spring qualities at each location, they will learn about the profound depths of hot spring culture cherished by locals.

Model Schedule

<Day 1>

13:30 Learn about the formation of hot springs at the Onsen Museum

15:00 Check-in to Kai Beppu

16:00 Make hot spring mist at Onsen Iroha @ Lab

16:30 Take a bath

17:30 Dinner

19:30 Enjoy the hot spring town

21:15 Local entertainment "Toji Jug Band"

<Day 2>

07:30 Breakfast

09:00 Experience hot spring dyeing @ Lab

10:00 Participate in the Jimo-sen tour

12:00 Departure

Adult's Free Research "What is a Hot Spring?" Overview

Period: July 20, 2026 - August 31, 2026

Price: 3,000 yen per person (tax included, accommodation not included)

Includes: Jigoku Onsen Museum admission fee, hot spring dyeing experience, Jimo-sen tour

Location: Kai Beppu, Jigoku Onsen Museum

Capacity: 4 groups per day (1-12 people)

Target: Guests of elementary school age and above

Reservation: Book on the official website at least 7 days in advance

URL: https://hoshinoresorts.com/ja/hotels/kaibeppu/

What is Kai?

"Kai" is a hot spring ryokan brand operated by Hoshino Resorts, with 23 facilities nationwide. Under the theme "Classic yet New," it pursues hospitality that incorporates the changing seasons, Japanese aesthetics, and tradition while adapting to modern needs. It also features "Gotochi-gaku" (local activities) to experience the region's traditional culture and crafts, and "Gotochi-heya" (local-themed rooms) to experience local culture. In the summer of 2026, "Kai Matsumoto" in Asama Onsen, Nagano Prefecture, will be...