"Extra quality" might refer to high-resolution assets or better graphics, which are sometimes available through modded versions or cracked apps. But I have to be careful not to suggest piracy. Instead, maybe talk about in-app purchases or premium versions that offer better visuals.
To make an older game like this look great on a modern 4K or 1080p monitor: tropical kiss game english download extra quality
While originally a Japanese PC title, "extra quality" or high-definition English versions typically refer to community-translated patches or later releases: Tropical Kiss Visual Novel Review - A Summer Paradise "Extra quality" might refer to high-resolution assets or