I have been reading this forum all day yesterday and I am still getting conflicting info. I am hoping that someone here can give me a correct answer.

I am booking an award flight from DFW to KUL with an overnight layover in NRT. AA from DFW to NRT and JAL from NRT to KUL.

There are 2 AA flights a day from DFW to NRT
departing 9:45am arriving 2:05pm
or
departing 12:40pm arriving 5:10pm

The connecting JAL connecting flight to KUL won't leave till 11:20am the next day.

I don't mind staying overnight in Narita provided that I don't have to carry all the bags with me. Is it possible to check the baggage all the way to KUL with the above itinerary. On one thread, posters mentioned about the 24 hours rule so either flights above should be fine since the layover will be less than 24 hours.
On another thread, someone posted that he/she was having difficulty checking the bags thru.

Based on my understanding of how things work, you should be able to check bags all the way through to KUL. As you say, the gap btwn flights is less than 24 hours. What's more, JAL and AA have very well established operations at NRT and they work together as alliance partners.

However, if you've discovered a thread where someone with direct, recent experience of this scenario is having difficulty checking luggage to his/her final destination, I can't deny the possibility that the situation has changed since I last looked into this. If you want to point us to the source of the information that's clouding the issue for you, people on this forum may be able to clear things up.