Flight Gimpo International Airport departs from Seoul Gimpo International Airport at 19:50 and arrives at Tokyo Haneda Airport at 22:00.
The flighttime is about 2h 10m. The distance travelled ("as the bird flies"): 1450 Km. So the average speed is roughly 669 Km.
The best day to arrive at Seoul is Saturday and it would be best to avoid Tuesday, as prices are on average 221.3% higher than on Saturday. (Average prices, based on 1086314 datapoints.)
We have a lot more statistics for flights OZ 1065 and between Seoul and Tokyo.