Originally Posted by
immunedata
On a HND to GMP flight a couple weeks ago on a 787-9 I was able to select JAL SKY PREMIUM seat at point of booking (few weeks before) which according to the table here is considered Premium Economy Class:
https://www.jal.co.jp/jp/en/aircraft/conf/789.html
My photos are rubbish but there's plenty of reviews online. It's a shell type seat which reclines to a good angle, legroom and width is good (being 190cm and 90kg). Better than the regional J seats at MAS. Food onboard was the standard Y offering but fortunately the JAL First Class lounge in Haneda is fantastic.

That’s helpful and provides clarity, thanks for sharing. It seems that if PY isn’t being sold separately on a particular route, in this case HND-GMP, they’ll have it available for select Y passengers for free or others for fee. The US carriers sometimes do something similar when positioning wide bodies domestically.
Free PY on long hauls for Y fares would be a game changer though, maybe too OP.