This is the lame SFW version of the game. It seems the dev want to forget the NSFW version...
You can install the game here and grab the adult patch though:
https://steamcommunity.com/sharedfiles/filedetails/?id=2598371332
Just check stickied information regarding "About the Nekojishi Limited Edition":
https://itch.io/t/1307483/about-nekojishi-and-discussion-rules