I'm not endorsing any outside connection, but looking at the gameplay that was posted there are definitely thematic similarities between Petscop and this game. They rely on the same techniques to endorse a sense of discomfort and fear in the player.

In the first few minutes of the Japanese game, you hear music/sound effects just like that in petscop. There is that synth crescendo, where it goes quiet to really loud.

Remember when you click on the CDs in p. 14 and it makes that sound effect? It's the same type of music this game uses.

It also uses long single notes for its music. When paul is looking at the windmill, a single low ominous note is played and held down for a while. In the J-game, it also is just play single notes on the piano, which just sounds fucking creepy.

Further reinforces that petscop is a psychological horror game and some thought was put into the techniques used (even if the game is incomplete).