Flight Narita International Airport departs from Tokyo Narita International Airport at 16:55 and arrives at Seoul Incheon International Airport at 20:00.
The flighttime is about 3h 05m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 504 Km.
The best day to arrive at Tokyo is Tuesday and it would be best to avoid Saturday, as prices are on average 357.59% higher than on Tuesday. (Average prices, based on 3798045 datapoints.)
We have a lot more statistics for flights 7C 1113 and between Tokyo and Seoul.