Just a follow up to this posting. I was able to get into the Flagship Lounge in LAX as well as JAL's FC Lounge in Narita without hiccup. In fact, when you check in in Narita, the JAL boarding pass automatically prints "First Class Lounge" on it. Also I got a preferred seat on the JAL NRT-SIN flight near the front.
The JAL Lounge is nice..nothing spectacular.
Link to photos:
http://flic.kr/s/aHsjLcR3q7