Flight Incheon International Airport departs from Seoul Incheon International Airport at 19:10 and arrives at Osaka Kansai International Airport at 21:05.
The flighttime is about 1h 55m. The distance travelled ("as the bird flies"): 1002 Km. So the average speed is roughly 523 Km.
The best day to arrive at Seoul is Monday and it would be best to avoid Saturday, as prices are on average 81.44% higher than on Monday. (Average prices, based on 1927519 datapoints.)
We have a lot more statistics for flights KE 721 and between Seoul and Osaka.