Hello, sadly true, the main game is not available for new purchases on itch anymore, only on provided websites:
[Uncensored version] https://saikeystudios.com/product/orks-ryona-bbc/
[Censored version] https://www.dlsite.com/maniax/work/=/product_id/RJ01019508.html
P.S.: the owners of the game on itch (which bought the game before it was disabled) can freely download the updated v1.8 game (the download link only shows if the game was purchased previously)
I hope this helps,
~NK