Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Kuantan to Osaka as you normally would.
Kuantan (KUA) is the airport you will fly out of if you book a flight from Kuantan to Osaka. You should not have trouble finding flights to Osaka from Kuantan; the airport handles an average of 0 outbound flights to Osaka per day. You should also have plenty of airline options to choose from since 0 airlines have flights from the Kuantan airport to Osaka. It is only a 12.7 km journey to Kuantan (KUA) from Kuantan’s city centre.