Please be aware that Osaka and Seoul has multiple airports and that these results are for all airports serving the city.
The best month to fly between Osaka and Seoul is July and the most expensive month to fly is February. (Average prices, based on 270 datapoints.)
The best day to arrive at Osaka is Wednesday and it would be best to avoid Monday, as prices are on average 154.6% higher than on Wednesday. (Average prices, based on 271 datapoints.)
The cheapest airline flying from Osaka to Seoul is Jin Air. They are 53% cheaper than Korean Air. (Average prices, based on 305 datapoints.)
The best time to fly is at around 15. (Average prices, based on 523 datapoints.)