NARAHA, Japan — The decontamination crews at a deserted elementary school here are at the forefront of what Japan says is the most ambitious radiological cleanup the world has seen, one that promised to draw on cutting-edge technology from across the globe.

But much of the work at the Naraha-Minami Elementary School, about 12 miles away from the ravaged Fukushima Daiichi nuclear power plant, tells another story. For eight hours a day, construction workers blast buildings with water, cut grass and shovel dirt and foliage into big black plastic bags — which, with nowhere to go, dot Naraha’s landscape like funeral mounds.

More than a year and a half since the nuclear crisis, much of Japan’s post-Fukushima cleanup remains primitive, slapdash and bereft of the cleanup methods lauded by government scientists as effective in removing harmful radioactive cesium from the environment.

Local businesses that responded to a government call to research and develop decontamination methods have found themselves largely left out. American and other foreign companies with proven expertise in environmental remediation, invited to Japan in June to show off their technologies, have similarly found little scope to participate.