Flight Narita International Airport departs from Tokyo Narita International Airport at 20:40 and arrives at Seoul Incheon International Airport at 23:05.
The flighttime is about 2h 25m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 643 Km.
The best day to arrive at Tokyo is Saturday and it would be best to avoid Sunday, as prices are on average 209.53% higher than on Saturday. (Average prices, based on 4526496 datapoints.)
We have a lot more statistics for flights ET 673 and between Tokyo and Seoul.
