Diplomatic ties were severed in 1941 with the start of the Pacific War.
During the war, Canada interned Japanese-Canadians after passage of the War Measures Act for 'national security' purposes.
Japanese-Canadians had many of their rights revoked, including the right to work in any occupation they choose as well as their right to own property.

In their only direct battle during the Pacific War, Japanese and Canadian forces fought one another during the Battle of Hong Kong, eight hours after the Attack on Pearl Harbor.
The battle ended with the Japanese occupation of Hong Kong.
Diplomatic ties were severed in 1941 with the start of the Pacific War. During the war, Canada interned Japanese-Canadians after passage of the War Measures Act for 'national security' purposes. Japanese-Canadians had many of their rights revoked, including the right to work in any occupation they choose as well as their right to own property.
In their only direct battle during the Pacific War, Japanese and Canadian forces fought one another during the Battle of Hong Kong, eight hours after the Attack on Pearl Harbor. The battle ended with the Japanese occupation of Hong Kong.
Canada–Japan relations