Please be aware that Jakarta and Osaka has multiple airports and that these results are for all airports serving the city.
The best month to fly between Jakarta and Osaka is September and the most expensive month to fly is August. (Average prices, based on 737 datapoints.)
The best day to arrive at Jakarta is Monday and it would be best to avoid Wednesday, as prices are on average 311.58% higher than on Monday. (Average prices, based on 737 datapoints.)