Flight Tan Son Nhat International Airport departs from Ho Chi Minh City Tan Son Nhat International Airport at 07:00 and arrives at Tokyo Narita International Airport at 15:05.
The flighttime is about 6h 05m. The distance travelled ("as the bird flies"): 3981 Km. So the average speed is roughly 654 Km.
There is an 2 hour time difference between Ho Chi Minh City and Tokyo