question already asked here. answer is same as above.
Seat selection on JAL on award tickets.
Business class:
Seat 1A (on 787s) is typically blocked for last minute cash bookings/VVIPs.
Opened up at check-in T-24h.
Rest of the seats, availability is based on your status for the FFP number on record.

As a one world Sapphire, you can select the following business class window seats
From row 5 on the 767, 787 and 772 (excludes rows 1-4 window seats)
From main cabin on the 777W (excludes whole of mini cabin)

As a non-status passenger (or Ruby member), you can only select the following business class window seats
From second row onward of second cabin on the 767, 787 and 772 (excludes all of the forward cabin window seats and first/exit row of main cabin)
From second row onward of main cabin on the 777W (excludes whole of mini cabin and first/exit row of main cabin)

As an Emerald, you have unlimited access.