This anime is based on the eroge of the same name created by Navel, though interestingly Shuffle’s manga version actually debuted a month before the game did. It’s worth noting that the manga is non-nude. The game is pornographic, and even has a fully uncensored / explicit version available.
It is a rare thing, to be emotionally impacted by a nudey anime. I actually teared up a bit and had to reach for a second tissue. Well done, asread.