Air Asia's foray into Japan is proving to be quite popular. In July 2012 I made a trip to Japan using Air Asia X - flying into Kansai Airport and flying out from Haneda Airport Tokyo. Breaking up the trip costs quite a bit more, but it means I do not have to backtrack to get back home.
Air Asia X uses Airbus 330 aircrafts. The seat arrangement is 3-3-3. Seats are the same as in other Air Asia aircrafts, but the spacing between seats is a bit more generous. The inflight crew included a few Japanese flight attendants which would be helpful if you are Japanese.
As this was a trip to Japan, I booked the Chicken Yakitori meal. Not bad.
All in the 6 hour flight to Osaka was quite smooth and pleasant. It arrived before 4.00p.m. as scheduled, and I took a train to the City.