On a recent morning, supermarket owner Takashi Nakajima expertly sliced into slabs of raw sea bream and horse mackerel, placing the thin wedges of the local Fukushima catch on a plate to be sold in the store he inherited from his father.

It's been a long battle to get radiation-wary customers back to the seafood from waters near the Fukushima nuclear power plant that was wrecked in the 2011 tsunami, Nakajima says. Now, with the imminent release of treated radioactive water from the plant into the Pacific, he fears a return to square one.

"This can't be happening," the 67-year-old said in the backyard kitchen of his supermarket in Soma, Fukushima Prefecture, just 45 km north of the stricken power plant.