Flight Narita International Airport departs from Tokyo Narita International Airport at 20:20 and arrives at Chengdu Chengdu Shuangliu International Airport at 00:40.
The flighttime is about 6h 20m. The distance travelled ("as the bird flies"): 4060 Km. So the average speed is roughly 641 Km.
There is an 2 hour time difference between Tokyo and Chengdu