Flight Haneda Airport departs from Tokyo Haneda Airport at 20:05 and arrives at Seoul Incheon International Airport at 22:35.
The flighttime is about 2h 30m. The distance travelled ("as the bird flies"): 1487 Km. So the average speed is roughly 595 Km.
The best day to arrive at Tokyo is Wednesday and it would be best to avoid Friday, as prices are on average 206.65% higher than on Wednesday. (Average prices, based on 1485102 datapoints.)
We have a lot more statistics for flights OZ 1035 and between Tokyo and Seoul.