The heavy rain showed no signs of letting up. The city had only just begun preparing for the sudden, intense storms in the forecast, and now it was about to be hit by disasters everywhere.
The worst was avoided thanks to centuries of diligent flood control and water-diversion efforts. The construction of railway lines in sparsely populated valleys and tunnels made flood prevention an essential matter, leading to measures like underground reservoirs and rivers being turned into channels.
Even in the Shinjuku Imperial Garden, where the water god was said to reside, the ponds that collected rain and groundwater not only absorbed a significant amount of rain but also allowed excess water to flow immediately over a small dam into the nearby underground channel. The fierce flow of water would push at the round, eroded stones submerged in the pond, along with the creatures swimming around in there, but as long as the dam remained, none of those objects would enter the underground channel.
But one stone submerged in the bottom of the pond—shaped like a long, thin blade—may have been more suited to catching the flow of water. Even in the early stages, when rainwater began to drain from the pond, it was already moving around. What set it apart from the pond’s other residents was that, despite being pushed against the small dam, its flat shape allowed it to be carried upward by the water flow, slip over the dam, and flow into the Shibuya River, one tributary of the underground channel system.
In the force of the water flow, it moved with an unusual lightness for being made of stone. It moved through the channel like a slightly heavy piece of wood, going from the Sendagaya neighborhood toward Jingumae. It flowed across narrow culverts between densely packed houses, streamed through underground channels where sunlight never reached, collided with concrete riverbanks as it crossed between Harajuku and Omotesando, and finally merged into the Onden River, another old body of water that had been channeled underground.
At the riverbed here, there were low dams constructed to prevent debris from pooling together. The stone got caught on these dams several times, but the force of the current was strong enough that it managed to keep moving forward.
After traveling approximately three miles through the underground waterways, the stone finally came to a vast reservoir beneath the intersection in front of Shibuya Station. There, it seemed to fall out of the current, sinking straight to the bottom and coming to rest.
Rainwater filled the reservoir, the overflow going out into the Shibuya River aboveground. But no matter how swiftly the water flowed, the stone remained motionless, firmly adhering to the bottom of the reservoir, seeming to find its home right above the ritual hall located even deeper below.