Flight Narita International Airport departs from Tokyo Narita International Airport at 18:50 and arrives at Seoul Incheon International Airport at 21:30.
The flighttime is about 2h 40m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 583 Km.
The best month to arrive at Tokyo is March and the most expensive month to fly is January. (Average prices, based on 5043 datapoints.)
The best day to arrive at Tokyo is Tuesday and it would be best to avoid Sunday, as prices are on average 25.88% higher than on Tuesday. (Average prices, based on 3413715 datapoints.)
We have a lot more statistics for flights GA 105 and between Tokyo and Seoul.