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 September and the most expensive month to fly is April. (Average prices, based on 543 datapoints.)
The best day to arrive at Osaka is Friday and it would be best to avoid Monday, as prices are on average 261.92% higher than on Friday. (Average prices, based on 268 datapoints.)
The cheapest airline flying from Osaka to Seoul is EastarJet. They are 45% cheaper than Jeju Air. (Average prices, based on 549 datapoints.)
The best time to fly is at around 13. (Average prices, based on 711 datapoints.)