Unclear why this is a "plus" edition, seems the same as the regular version.
The differences from the standard Super Pink Sox 3 were that it was mail order only, had a text indicating it was the + version preannounced in the standard version, and had several graphics without underwear. Its title graphic was unchanged unlike the PC9801 version Plus one with + symbol: https://refuge.tokyo/pc9801/pc98/02019.html
The manual is same as the standard version.
This package release that was distributed by Takeru outside their vending machine features very few nudity despite being part of the Pink Sox adult series and displaying "R18 version" on its package. It is not confirmed to have been preceded by any "all ages version".
The manual is same as 3+.