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 June. (Average prices, based on 1108 datapoints.)
The best day to arrive at Tokyo is Wednesday and it would be best to avoid Monday, as prices are on average 46.45% higher than on Wednesday. (Average prices, based on 3801186 datapoints.)
We have a lot more statistics for flights GA 105 and between Tokyo and Seoul.