Flight Haneda Airport departs from Tokyo Haneda Airport at 08:25 and arrives at Seoul Gimpo International Airport at 10:45.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 1450 Km. So the average speed is roughly 621 Km.
The best day to arrive at Tokyo is Saturday and it would be best to avoid Friday, as prices are on average 180.62% higher than on Saturday. (Average prices, based on 388512 datapoints.)
We have a lot more statistics for flights JL 91 and between Tokyo and Seoul.
NZD
