Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Singapore City Airport to Kumamoto as you normally would.
The Singapore Changi to Kumamoto flight path was viewed by 1,652 users in the past month. Keep an eye out for changes in search interest prior to high and low season.
Due to the rapidly changing circumstances due to COVID-19, airlines like Japan Airlines flying from Singapore Changi to Kumamoto have implemented new flexible change policies.