Flight Incheon International Airport departs from Seoul Incheon International Airport at 08:10 and arrives at Tokyo Narita International Airport at 10:25.
The flighttime is about 2h 15m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 691 Km.
The best day to arrive at Seoul is Wednesday and it would be best to avoid Saturday, as prices are on average 188.14% higher than on Wednesday. (Average prices, based on 6764077 datapoints.)
We have a lot more statistics for flights RS 705 and between Seoul and Tokyo.