Original:  British rule was suspended in February 1942, when the Imperial Japanese Army of the Japanese Empire had invaded Singapore during the Pacific Front of World War II and renamed it Syonan-to . After the war, Singapore was returned to British rule. It subsequently separated from the Straits Settlements itself, and became its own standalone crown colony with its own governor.
Revised:  British rule was suspended in February 1942, when the Imperial Japanese Army of the Japanese Empire had invaded Singapore during the Pacific Front of World War II and renamed it Syonan-to . 
Edit intent: coherence