To see a wider selection of flights to Osaka, try searching by city rather than by airport.
The cheapest airline to fly to with is normally Cathay Pacific. Play around with the search options to see what you can find.
Accommodation costs will also be higher at this time of year. To get an idea of hotel prices in Japan, search with Netflights. We do car hire price comparisons too.
To get the flights you want, it's best to book as far in advance as possible – prices of both flights and accommodation tend to increased the closer you are to departure. To check hotel prices in Osaka, simply use the tabs at the top of the page.