Mr Reti said there was an obvious connection between the two countries because of Japan's experience and New Zealand's world-leading anti-nuclear stance.
The Japanese also liked the fact Mr Reti could speak Japanese fluently.
He was unsure when the official invitation to the commemoration would come but indicated he would like to attend, even if not as a government representative.
The 70th commemoration would provide another international forum to discuss hastening disarmament in line with the terms of the 45-year-old NPT, he said.
In recent years, France has cut back to 300 nuclear weapons, the UK is currently holding 200 weapons and the US and Russia have reduced their stockpiles.
But Russia is now standing still, saying it needs nuclear capability because of unstable neighbours and the US has announced a $1 billion annual commitment to maintaining its stockpile, saying the ageing armaments must be kept in safe condition.