Flight Kansai International Airport departs from Osaka Kansai International Airport at 20:40 and arrives at Seoul Incheon International Airport at 22:25.
The flighttime is about 1h 45m. The distance travelled ("as the bird flies"): 1002 Km. So the average speed is roughly 573 Km.
The best day to arrive at Osaka is Sunday and it would be best to avoid Saturday, as prices are on average 296.54% higher than on Sunday. (Average prices, based on 5022815 datapoints.)
We have a lot more statistics for flights OZ 1155 and between Osaka and Seoul.