Arai noted that the Russian law states that a safe level of radiation is up to 1 millisieverts a year. "Japan prefers not to clarify this. Japan says that 20 millisieverts [a year] is ok," Arai said.

Japan also requires that all residents, who have left their homes following the Fukushima nuclear disaster, must return to their homes, while the Russian law gives people the right to move to a permanent residence in another place.

According to Arai, 70 percent of people who have left their homes, will not return, regardless of what the Japanese government tells them to do.

Arai noted that countries that have passed legislation, like the Chernobyl one, "greatly surpass Japan in terms of health protection and the protection of human rights."

On March 2011, the Fukushima Daiichi nuclear power plant was hit by a 9.0-magnitude earthquake and a subsequent tsunami, which caused a partial meltdown of three of the plant's nuclear reactors. The radiation from the plant leaked into the atmosphere, soil and sea.

The incident is the world's worst nuclear disaster since the Chernobyl catastrophe of 1986. Full liquidation of its consequences is expected to take about 40 years.

Japan's central government is responsible for decontaminating evacuation zones in 11 of the country's municipalities, where annual radiation levels exceed 20 millisieverts.