Emperor Akihito traced the history of exchanges between Japan and Poland during a Tuesday night speech he gave at a dinner hosted by Polish President Aleksander Kwasniewski.
The Emperor, who arrived in Warsaw earlier in the day with Empress Michiko, referred to the Rev. Maksymilian Maria Kolbe from Poland, who engaged in missionary work in Nagasaki between 1931 and 1935.
After returning to Poland, Kolbe was executed in the Nazis' Auschwitz extermination camp.
"A tragedy like that should never be repeated," the Emperor said in reference to Auschwitz at the dinner held at the presidential office, attended by about 90 people.