4 in business is possible on JAL, at least from the west coast. But you need to stalk around calendar open. We're doing SFO-NRT on JAL booked with BA. It was 77,250 Avios and $284 taxes, one-way, per person. On the way back, CTS-HND-SFO for 89,750 Avios and $301 taxes. BA charges by segment, so it was a bit expensive to add CTS-HND, but I wanted it on one ticket.
Last trip, we also did JAL in biz through AA. SJC-SEA-NRT, KIX-LAX back. It was 60k AA one-way, per person. Booked before Japan opened and flying on Christmas Day lol. AA calendar opens later than BA, so I don't anticipate being able to book with AA for 4 again.
It's also possible to book through Cathay, which I've never done. It costs 89k, but I think they're region based, so more advantageous for east coast. BA is distance based. They release 5 days earlier than BA. But redeposit fee is more ($120), BA is $55, AA is free.