Flight Haneda Airport departs from Tokyo Haneda Airport at 11:35 and arrives at Kagoshima Kagoshima Airport at 13:30.
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 Friday and it would be best to avoid Tuesday, as prices are on average 189.59% higher than on Friday. (Average prices, based on 390836 datapoints.)
We have a lot more statistics for flights NH 623 and between Tokyo and Kagoshima.