In addition to abundant ala carte veg options, there is a dedicated menu that you can preorder.

***http://www.jal.co.jp/jp/en/inter/ser..._251201.pdf***

Looks really tasty to me!

As for making use of OW Sapphire, when returning from HND, you can use the Sakura Lounge (two of them—I recommend the Sky View one for smaller crowds/better views). But also be sure to check out the Cathay Pacific Lounge. Stunning interior, great food with veg options and you can use it even if flying on JAL. And best views from the top floor.