Japan is crediting former Prime Minister Helen Clark for turning New Zealand into "one of the best friends Japan could wish for".
The Japanese Ambassador to New Zealand presented Clark with the Grand Cordon of the Order of the Rising Sun, at an investiture ceremony in Wellington this evening.
It is the highest award in Japan's honour system.
Ambassador Toshihisa Takata said the honour was to recognise Clark's contribution to bringing Japan and New Zealand closer, both when she was Prime Minister and in her time as the administrator of the United Nations Development Programme.
"All throughout these years of unwavering commitment and dedication as a leading official of the New Zealand Government, and the UNDP, Ms Clark visited Japan at least 20 times.
"One of the top records for such visits, by such a renowned and highly regarded foreign dignitary."
Takata said that when Clark was Prime Minister she helped realise several high-level exchanges between our countries, including receiving Japan's Crown Prince and Crown Princess to New Zealand. Clark also visited Japan during the Aichi Expo.
He said the exchanges led to a deeper understanding between the two countries, most importantly between Japanese and New Zealand citizens.
"The feeling of being energised and encouraged is common to everyone who come into contact with Helen Clark, either directly or indirectly," Takata said.
"She's one of the best friends Japan could wish for, not only in New Zealand but also in the international community."
Clark is also credited with promoting the relationship between Japan and the UNDP while she was administrator, on issues such as eradicating poverty and realising sustainable development, and showing support for Japanese initiatives such as the Tokyo International Conference on African Development.
Clark said she was "deeply honoured" to receive the award.
She said her relationship with the country predated being any kind of public figure, as in 1975 she was part of a delegation of young New Zealanders chosen to take part in the Japanese Youth Goodwill Cruise.
She said it sparked a lifetime interest in Japan.
"What I came to appreciate, in my time in public service in New Zealand, was that Japan was such an incredibly important partner for us.
"When I started out in public life there weren't so many democracies around the Asia Pacific Rim. Japan was one.
"We very much valued the ability to talk to Japan as a friend. Of course the trade and security was important, but the relationship had much more depth than any commercial relationship might indicate."
The Order of the Rising Sun was established in 1875, with the highest possible rank being the Grand Cordon.
It's awarded to people who distinguish themselves with achievements in international relations, promotion of Japanese culture, military achievements, or advancements in their field of expertise.
It is the highest honour able to be freely given in Japan, with the only higher titles reserved for Japanese royalty and politicians.