After WWII, Kaga city in Japan made a declaration for world peace in response to the call for a unified world made by Nobel laureate Dr. Hideki Yukawa. The twinning of Dundas and Kaga was initiated by an exchange of letters between Dundas Mayor Leslie Couldrey, Dr. Hanna Newcombe (of the Peace Research Institute in Dundas) and Kaga Mayor Higashino.  The Dundas initiative was supported by many "world as one" citizen groups such as the Dundas Lions Club.  The official declaration of Kaga-Dundas twinning occurred in Kaga on March 21, 1968.  In Dundas the official twinning ceremony was held at Dundas Driving Park Band Shell on  September 21, 1968. On December 3, 1968, Canadian Ambassador H.O. Moran and Kaga Mayor Higashino signed the twinning proclamation in Kaga.  Dundas became the first mundialized municipality in North America. The twinning of Kaga and Dundas is the longest lasting East-West  exchange program and a unique way to build world peace through student exchanges as well as municipal exchanges.

Two twin city committees were established in Kaga and Dundas to facilitate the student exchange. In Kaga the sister committee was named Dundas Tomono-kai, in Dundas the corresponding sister committee was named Kids for Kaga. The first exchange took place in 1970.  The first exchange group led by teacher Julie Ashcroft consisted of  32 students and chaperones left Dundas on June 16,1970 for three weeks of exchange. The first exchange Kaga students and chaperones of 46 arrived in Dundas on August 1, 1971.  Many strong family ties have been formed between the students and the families through the "home stay" (hosting) program, and regular exchanges between Kaga and Dundas have continued on a three year regular rotation.