Originally Posted by JH1981

If you are not a OW Sapphire or Emerald, you can not enter JAL lounge without flying F or J on JAL... unless CX doesn't operate their own lounge at that airport and the JAL lounge has been designated as the handling lounge for CX passengers ... in which they would have some sort of display at the entrance with the CX logo... at NRT, CX does operate their own lounge.

Think of OW as an alliance of mileage programs not an alliance of all airline operation. If you notice the entrance of all lounges, it clearly informs you who does or does not have access to the lounge. For example, the CX lounge in HKIA would say "First Class Lounge" and underneath that would have a OW logo followed by a green oval.