Flight Haneda Airport departs from Tokyo Haneda Airport at 10:05 and arrives at Kagoshima Kagoshima Airport at 12:00.
The flighttime is about 1h 55m. The distance travelled ("as the bird flies"): 1048 Km. So the average speed is roughly 547 Km.
The best day to arrive at Tokyo is Monday and it would be best to avoid Tuesday, as prices are on average 366.68% higher than on Monday. (Average prices, based on 393724 datapoints.)
We have a lot more statistics for flights JL 645 and between Tokyo and Kagoshima.