Located on the western edge of Shimoji Island in the Town of Irabu lies Tori-ike, a mysterious body of water surrounded by a barren rocky plateau. Visitors have called it the devilfs mouth.

Tori-ike is about 35 meters deep and has an eroded natural rock bridge crossing its center. Although appearing to be landlocked, it is connected to the ocean by underground water passages. The dark blue waters of this loch always seem to remain calm, even when winds blow across the lonely plateau.

The story of how Tori-ike was formed is told by an old folktale of Irabu. Once, there was a fisherman who caught a strange creature whose features were half human and half fish. It was a yonaitama, a legendary animal about which he had heard in stories told by the old people of his village. It was said that the meat of the yonaitama would give eternal youth to anyone who ate it, so the fisherman invited his friends over to share his extraordinary catch.

When all was prepared for the great feast, there suddenly was a gigantic roar and the earth shook. The ocean swelled into mountainous billows and towering waves swept over the island where the fishermanfs village stood.

After the angry seas eventually calmed and the waters ebbed away, nothing could be found of the village. All the homes, trees, and even the ground had been swept away, leaving the pond-like body of water carved in the bedrock where the strange creature was about to be roasted.