Flight Narita International Airport departs from Tokyo Narita International Airport at 13:25 and arrives at Fukuoka Fukuoka Airport at 15:40.
The flighttime is about 2h 15m. The distance travelled ("as the bird flies"): 1119 Km. So the average speed is roughly 497 Km.
The best day to arrive at Tokyo is Wednesday and it would be best to avoid Monday, as prices are on average 400% higher than on Wednesday. (Average prices, based on 1293683 datapoints.)
We have a lot more statistics for flights JL 6051 and between Tokyo and Fukuoka.