The Oki Islands appear in the myth of Japan’s creation written in the Kojiki, or the “Records of Ancient Matters” compiled in the early 8th century. Recorded there as “mitsugo-no-shima,” meaning the triplet islands, they appear third in order of creation after Awaji Island and Shikoku. But there are four inhabited Oki Islands, so why triplet islands? One interpretation is that “mitsugo-no-shima” actually refers to the three Dōzen Islands: Nishinoshima Island, Nakanoshima Island, and Chiburijima Island. In this theory, Dōgo, where you are now, is considered the “mother island” and the triplets are the “children.” In fact, Dōzen and Dōgo are area names, and while the Dōzen Islands have individual names—Nishinoshima, Nakanoshima, and Chiburijima—Dōgo’s island has no name. It is the only inhabited island in Japan without a name. So why was the island not named? There are various theories, but one is that because Dōgo is the mother island, it was thought unnecessary to give it a name.

Islands of Exile

In Japan, the Oki Islands are known as the place where two former Japanese emperors were exiled. In fact, the Oki Islands were the only place where emperors with the power to start an attack against the shogunate could be exiled. Why is this? We can find a clue in the history of Oki abalone. Since the Heian period, the period from 794 to 1185, abalone from the Oki Islands was dedicated as an offering to new emperors when ascending to the throne. It was also given as a bonus to people of the minister class. However, governors and people of classes below this could not receive it.

Why was Oki abalone treated as the highest quality brand? The reason for this lies in the location of the Oki Islands. They are northwest of Nara and Kyoto, which were the capitals at the time. This direction was believed to bring good omens, so the abalone from here was used. The same reason is part of why these islands were chosen as a place of exile: an emperor planning to overthrow the shogunate must be sent far away, to a remote island where he cannot easily return to the capital. However, because he is an emperor, he must be sent in a direction of good omens.

Everything Began with Obsidian

The Oki Islands were chosen as islands of exile during the Nara period, in the 8th century. This means that since that time, it has been known what kind of place these islands are. The reason for this can be seen through a rock called obsidian. Please move to the obsidian exhibit, where a large black rock is on display.
Obsidian is a rock that was used to make stone tools long ago, from the old stone age through the Jomon and Yayoi periods. Within Japan, there are more than 100 known obsidian localities, or sources where obsidian can be found. However, only obsidian of high enough quality could be used for stone tools. Because of this, there are only about six major obsidian localities in Japan that were used for stone tools, including the Oki Islands. It is known that obsidian from the Oki Islands was transported as early as 30,000 years ago, mainly around the Chugoku region. In other words, the Oki Islands were well known since ancient times because of the exchange of people and culture that was brought about through obsidian trade.

Now let’s step out into the Geopark and take a trip around the Oki Islands. As you visit each site, please take a moment to listen to the corresponding audio guide.