It’s easy to see where this rock formation near the southernmost tip of the Kii Peninsula gets its name:  the Bridge Pier Rocks.  The straight line of craggy points of rock heading offshore toward Kii Oshima island looks like the remnant piers of a long-lost bridge to the island.  So much so that it’s hardly surprising there’s a legend explaining them.

The surprise is that the legend attributes the rocks to Kobo Daishi (774-835), the Buddhist monk who is credited with the invention of the kana writing system as well as popularizing Buddhism by travelling the length and breadth of Japan founding temples. (At least, I would have expected a much older tale.)

So, here’s the story. In his travels, Kobo Daishi came to the town of Kushimoto in present day Wakayama Prefecture. Soon after he arrived, the townspeople came to request his assistance. It seems they  had been trying to build a bridge to Kii Oshima from the mainland, but the local “monster” (or “devil”, if you prefer), Amonojaku, kept destroying their work. They appealed to Kobo Daishi to intercede on their behalf with Amonojaku.

When Kobo Daishi met Amonojaku, the latter agreed that he would allow a bridge to stand if, and only if, the bridge had been built by Kobo Daishi himself, acting alone without assistance. Amonojaku added the condition that the bridge must be built in a day and a night. When Kobo Daishi objected that such a task was impossible for anyone, Amonojaku helpfully offered to give Kobo Daishi the strength of 100 horses.  But he stressed that the bridge must be completed by the time the cock crowed the following morning.

Kobo Daishi set to his task, industriously gathering boulders from the mountains and piling them into piers for the bridge. Kobo Daishi was so industrious, in fact, that Amonojaku began to fear that Kobo Daishi would, in fact, manage to construct the bridge, in spite of Amonojaku’s impossible conditions.

So Amonojaku did what any would-be-thwarted monster would do in his place. He cheated.

In the dark of night, when it was not yet near sunrise, Amonojaku faked the crow of a rooster, causing Kobo Daishi to think it was dawn and he had lost the challenge. Kobo Daishi stopped work. Amonojaku won. And the “unfinished bridge” juts out into the sea to this day.

Of course, there’s a geological explanation for this phenomenon as well. Predictably, it relates to volcanic activity. The rocks are the results of an upthrust of rock layers that included line of cooled magma about 15 meters wide. Once the layers reached the surface, the softer “mudstone” surrounding the magma eroded away, leaving the harder igenous rock, sometimes standing as much as 90 meters tall and stretching for some distance along the shoreline and out to sea. With the best efforts of the elements some of the rock has worn away, leaving the pier-like formations we see today.

Evidence of the erosion of the piers includes a field of smaller rocks just inland from the line of the “piers”, believed to have been left there in the aftermath of tsunamis that have struck this coast over the years, the most recent one being in 1944.

At low tide, it’s fun to wander among these rocks and check out the tide pools.

The Hashigui-iwa are 3-4 minutes by bus or taxi or 25-30 minutes on foot from Kushimoto Station. If you’re really intrepid, you can explore the extent of the formation inland or further out to sea beyond Kii Oshima. Other things to see in the area include the small US-Japan Friendship Museum (commemorating a trade incident 62 years before Commodore Perry’s blackships), the Turkish Sailors Monument (commemorating a fatal shipwreck in 1890) and the lighthouse.