“The seashore has hardened into concrete, and the scenery of unending gray tetrapods piled on top of one another is what you can see everywhere in Japan. It has changed into something irritating and ordinary. When you look at this seashore, you can’t tell whether it is the coast of Shonan, the coast of Chiba, or the coast of Okinawa.”
Tetrapods may be an unfamiliar word to readers who have not visited Japan and seen them lined up by the hundreds along bays and beaches. They look like oversize jacks with four concrete legs, some weighing as much as fifty tons. Tetrapods, which are supposed to retard beached erosion, are big business.
— Alex Kerr, Dogs and Demons: The Fall of Modern Japan (p 18)
In Japanese, the monstrous concrete formations lining the coasts are called shouha negatame. In English, they are referred to by their mathematical shape of tetrapod. It is estimated that nearly 50 percent of Japan’s 35,000 kilometer coastline has been covered or somehow altered by Tetrapods and other forms of concrete (wikipedia).
Following the postwar trend to encase everything in concrete, the coast line has joined the rivers and mountains in their submission to the mammoth industry that is construction in Japan. It’s an interesting paradox for a country that is stereotypically known for natural beauty. In reality, Japanese bureaucracy has paved the way for one of the world’s largest construction industry, whether it’s needed or not.
The above picture is of Beppu Bay and is a 3 minute walk from where I live. The concrete blocks here are slightly different, in triangle form, rather than the usual tetrapod.