Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 01:15 and arrives at Osaka Kansai International Airport at 09:20.
The flighttime is about 6h 05m. The distance travelled ("as the bird flies"): 3931 Km. So the average speed is roughly 646 Km.
There is an 2 hour time difference between Bangkok and Osaka