SHIMANTO, Kochi Prefecture--Locals have puzzled for years over who--or what--is behind a beloved piece of stone art here that balances a big heart-shaped stone by a stream so it appears to float in the air.

No matter how often the artwork is toppled over, someone or something, sets it back up, leading some to speculate if a phantom or demon might be rebuilding it. 

The question of its creator gripped the imagination of regulars in the area so strongly that they started a survey this summer to figure out the riddle at the river known as Japan’s last clean body of water.

The heart-shaped stone found along the majestic Shimantogawa river has become so popular it has drawn attention as a new tourist spot.

It has also proven a hit among people just visiting the stream for leisure purposes.

The artwork dubbed the “stone of love” by locals stands on the river beach far upstream from the mouth of the river in Shimanto city.

Stretching over it in the Nishi-Tosahage district of the municipality near the border with Ehime Prefecture is the Hagechinkabashi bridge, near which the JR Yodo Line runs.

Standing 45 centimeters tall and 40 cm wide, the 15-kilogram stone’s edges have been rounded down by the fast water flow of the great river.

The stone is supported by pebbles used as a base. It is so well-balanced it looks as if it's floating in the air under the summer sun.

The Hagechinkabashi bridge is on the course of the River Shimanto Ultra Marathon, an annual event organized in autumn. A reporter covering the event noticed the peculiar stone on Oct. 20 last year.

He also visited there in November, February, March and June to see it. Locals said torrential rains and storms knocked it over. But whenever the reporter went there, the stone was standing, though in slightly different positions and facing different directions.

Now, the mystery of who built it has finally been unraveled.

On Aug. 2, the long trail of interviews ended with an answer from a guide accompanying a group of rafters taking photos by the special stone.

A human, after all, and not a “kappa” or amphibious demon, has been setting up the heart-shaped stone all along.

“It was Takki. Only he can do it,” the guide said.

Takki turned out to be Hidetoshi Takimoto. The 54-year-old, who works as a nature guide at Forest Canyon Inc., an outdoor tour organizer based in Matsuno of nearby Ehime Prefecture, said he found the heart-shaped stone three summers ago.

Takimoto spotted it at the bottom of the river at the foot of the Hagechinkabashi bridge. Captivated by the “beautiful object,” he yanked it out of the water and lugged it up to the side of the river.

He said he knew right then “it might become a symbol of or a memorial to my favorite place, Shimantogawa.”

Takimoto learned how to sort out good stones and the way to erect them from a mason he met while previously working as a construction site manager.

After setting up the stone artwork near the water, he continued to care for it over the years. Following typhoons, heavy rainfall and floods, Takimoto came to the river to set his artwork back up again after it had toppled over on 40 occasions.

In the sweltering summer heat on Aug. 5, Takimoto gave the participants in the rafting tour a demonstration of how he gets the big heart-shaped stone to balance on top of the large stone that provides its base.

Takimoto first prepared the large stone he used for the artwork's base by adeptly arranging pebbles from the riverside on top of it. He then cradled the heart-shaped stone in both arms and carefully deposited it atop the pebbles.

The crowd broke into cheers as Takimoto slowly released the heart-shaped stone from his grasp less than a minute later, leaving it to stand freely on its own. "Amazing!" gasped one person watching.

The key to getting the artwork stable, Takimoto said, is making sure the heart-shaped stone is centered on the pebbles.

The stone artist said he "hopes the novel coronavirus pandemic will end soon and people will come see the 'stone of love,' as it will bring them good fortune.”

Though he said he worries about his artwork being washed away by days of torrential rain or typhoons, recently someone else besides the artist has begun dropping by to reset the stone after it has toppled.