Outraged, Mr. Yoshizawa began returning to his ranch soon after to feed the remnants of the herd he had been tending. He eventually decided to return full time to turn the ranch into a haven for all of the area’s abandoned cows. Of the approximately 360 cows at his 80-acre spread, more than half are ones that others left behind.

Although he describes his protest in mainly political terms, his explanation for returning despite the possible danger is tinged with a hint of emotion. He describes his horror on visiting abandoned farms where he found rows of dead cows, their heads fallen into food troughs where they had waited to be fed. In one barn, a newborn calf hoarsely bawled next to its dead mother. He said his spur-of-the-moment decision to save the calf, which he named Ichigo, or Strawberry, was his inspiration for trying to save the others left behind.

He still searches the evacuation zone for the often emaciated survivors, which he often has to pull by their ears to get them to follow him home. He tries to dodge police roadblocks; it is technically illegal for anyone to live inside the evacuation zone. Nonetheless, he has been caught a half-dozen times and forced to sign prewritten statements of apology for entering the zone. He has done so, but only after crossing out the promises not to do it again.

Mr. Yoshizawa is no stranger to challenging authority, having protested against nuclear power before. But he says he felt particularly bitter after the Fukushima accident, which he fears could permanently ruin the ranch that he inherited from his father.

It does not help that his town, Namie, felt especially deceived by its leaders. After he heard the explosions at the plant, whose smokestacks and cranes are visible from his kitchen, he and many other townspeople ended up fleeing into the radioactive plume because the government did not disclose crucial information about the accident.

“I needed to find a new philosophy to keep on living,” said Mr. Yoshizawa, who is unmarried and lives alone on the ranch. “Then I realized, why is Japan being so meek in accepting what authorities are telling them? I decided to become the resistance.”

On a recent cold morning, Mr. Yoshizawa used a small bulldozer to carry bales of yellow rice stalks to feed the cows, about two to three times the number that he says his ranch can sustainably support. The cows, mostly a breed known as Japanese Black prized for its marbled wagyu-style beef, hungrily mooed as they jostled one another to get a mouthful.