What does the Steam restoration patch do?
All the content seems to be in game already
Kagura's restoration patches are external patches that are applied to the Steam version due to different laws, Steam forces us to censor certain content, so the solution that Kagura took to avoid having to censor anything is to sell the game without any sexual scene in order to be sold on Steam. and offer an external patch to restore that content that was deleted. For example, if the game were sold on Steam without any restoration patch, they would have to eliminate the shota route, but thanks to this external patch you can restore this route again without Steam saying anything anymore, that complies with the rules, the external patch is something optional that the player applies taking responsibility.
and you can say well it's not a big deal but the law is the law and it must be followed especially in westy where there are many red lines (of moral hypocrisy)
luckily these do not apply to fantasy content or drawings but many times it is done to avoid cancellations or criticism because it is not (morally correct)
So many games that come from Japan need a restoration patch and that's how they bypass the legal loophole in steam
steam washes his hands because it sells a game that does not violate the rules and the player can access that content thanks to an external patch so we all win, steam sells, the company that localizes the game also sells too, and the player does not have to suffer censorship
Another important thing is that this content restoration patch also works as a patch to fix errors, so it is mandatory to apply it to increase the version and fix any bugs that the game may contain such as missing images or the game crashing or any errors in the translation