JAL Mileage Bank - Upgrade Yokoso Air Pass flights?

Out of curiosity does JAL allow you to upgrade Yokoso air pass segments? I can't seem to find any pricing regarding the upgrade for these.

Thanks!

I wasn't given the option in may...

admittedly, we had basically 30 seconds to catch the plane after we got to the counter so it's possible that we didn't have the chance to get it.

flights in japan are quite short, so coach is not really that bad.

I'd thought class J is kind of like putting down 1000 yen on the desk and you'd get the seat as long as it's available - I read somewhere either here or on the CX forum someone on an Asiamiles redemption ticket was able to get the seat on CTS-HND. Thought it's worth the money if you flight is that long (or, say the Okinawa flights). Otherwise it'd be quite silly- then again, 1000, for the entire trip in japan is a relatively small sum... if you see it as a different experience, it's "merely" 7 GBP or 10USD/EUR...)

Yes, I was wondering about those 1000 Yen upgrades in particular...