There are zero airlines offering flights to Osaka. The most direct route isn’t necessarily the cheapest – being flexible is key to finding the lowest airfare rates. For example, try searching by month to see the best time of the week to fly.
Osaka Itami Airport is just one of the airports in Osaka. If you're not set on a specific airport, try changing your search from Osaka Itami Airport to Osaka to see a broader range of flights – they might be cheaper.
If you're planning on going to Osaka during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.