The main FRA OneWorld lounge in T2 is the JAL Sakura lounge. The first part of this lounge has restricted opening hours as it is mainly there to serve JAL customers. It is nothing special anyway – if you arrive within a couple of hours of the JAL flight, it is likely to be very busy and the extra hot food options will most likely be gone by that time. And the standard food options in both parts of the Sakura lounge are unfortunately very German rather than Japanese. Personally, I would not make a journey for this lounge.