We can easily assume that idea of Onsen originated from where hot water springs out naturally. The oldest record of hot springs dates back to the era of Prince Shotoku. It is a record on Dogo Onsen situated on the outskirts of Matsuyama city in Ehime prefecture on Shikoku Island.

According to Iyo Fudoki (local records of the Iyo region), Prince Shotoku visited Dogo and enjoyed its hot spring, accompanied by the Goryeo priest Eji and Katsuragi-no-omi. He was very touched by the superior quality of the hot spring and expressed such strong emotions in Chinese writings. He incised an inscription on a stone and placed it in Yuoka. Although the epigraph itself is gone, the writing is recorded in "Shakunihongi" as cited from the Iyo Fudoki, and has been regarded as a precious document on ancient times.

Muro-no-yu of the Kii region and Arima of Harima have been known for its hot springs since antiquity. But these were only mere hot spring. In fact, the only location known as "Yuno-gun" (hot spring county) was Dogo. Onsenkyo (hot spring village) as known today may have started in Dogo. In this sense, Prince Shotoku may have been to our surprise an Onsen freak.

But when we come to think of it, Prince Shotoku resided in Nara, a part of Ikaruga, whereas Dogo is in Ehime. It would understandable for him to embark on an expedition to fight a battle. But to travel there just for the sake of a hot spring the distance was quite far. Of course, this may indicate how widespread the reputation of Dogo hot springs may have been. But when it comes to whether such episode was a historical fact or not, there are some criticisms. Seiichi Oyama who argues that Prince Shotoku never existed, straightforwardly asserts that Yuoka Epigraph is a forgery created during the Kamakura era. He claims it as only a fictional tale. Leaving the question of whether such is a historical fact or not aside, it is true that Dogo has been famous since antiquity. We also cannot deny the possibility that some elements relative to the legend of Prince Sotoku may have existed in the first place. Then what could be the element that connects Prince Shotoku and the Onsen? One day in May 2000, I left for Dogo to solve this mystery.

At the side of a narrow alley in the hot spring area was the stone monument on which the Yuoka epigraph was incised. And beside it was a sign describing its origin. The famous Dogo onsen is about 2 to 3 minutes walk from the place. Unfortunately, I didn't have the time to enjoy the onsen, but I noticed something interesting.

The area Dogo onsen is located is called Yuoka, probably meaning a hill where hot water springs out. As its name signifies, there is a small hill nearby. Since it offers a view of the whole of Matsuyama city, a castle was once situated on top of this hill. The castle is now a park called "Yuduki Castle". Its Chinese characters certainly provide an image of onsen. According to its history, the name came from the name of the hill that was once called "Yuduki-no-oka".

When I first saw this name, it suddenly reminded me of the "Yutsugi shrine" of Oomi and Shizuoka. It has the character "yu" which represents "hot water" in its name but has no relationship with onsen. It was named after the deity "Yuduki-no-kimi".

As you may know "Yuduki-no-kimi" is the person who led the Hata clan from the Korean peninsula to Japan. In other words, he was the chief of the Hata clan. Yuduki became Yutsugi with the addition of the Chinese characters "yu" and "tsugi" .

Returning to "Yuduki-no-oka" of Dogo onsen, the same sound can also be expressed with Yuduki. What if its original name had been "Yuduki-no-oka" Then the Hata clan must have named it.

In addition, the close advisor of Prince Shotoku who is said to have incised the Yuoka epigraph was Hata Kawakatsu. He was the leader of the clan and was called Uzumasa (Big Hata). As long as Hata Kawakatsu supported Prince Shotoku, the entire Hata clan would also have backed him.

If this could be true, can't we think that Hata clan had taken part in the Prince Shotoku legend of Dogo onsen? The Hata clan did have a high level of civil engineering. With that they could have discovered a natural hot spring and developed it into a spa resort. Perhaps the Hata clan founded Dogo onsen.

Translated by Rie Ishida