From following sales over the years, classical/opera are a niche-within-a-niche collector's market.
Classical production jumped quickly to Digital Audio to increase dynamics and quality (noise, hiss, etc.).
The story is very similar to jazz releases.
Japan LD releases were either straight imports from USA/Europe (not many Operas recorded in Japan!).
But for some recordings, during Japan economic bubbles, they were able to purchase release rights of some rare materials/recordings that only got Japan release.
Currently showing up in searches:
Opera / Japan release =>
450(note that I made a timeline with matching searches here for Operas:
https://www.lddb.com/opera.php)
Classical / Japan release =>
541But a LOT of these were released multiple times, so the actual count of distinct releases is much lower.
Ex #1
Teldec (Warner Classics):
WPLP-xxxx =>
WPLS-xxxxEx #2
Pioneer Classics:
SMxxx-xxxx =>
PILC-xxxxEx #3
Sony Classics:
SRLM xxxxEx #4
Philips:
xxVC-xxx =>
CDV-xxxx =>
PHLP-xxxxEx #5
Deutsche Grammophon:
WxxZ xxxxx =>
POLG-xxxxEtc.
Happy hunting!
Julien