Yeah because it's a Japanese game, not Korean. Where it's made doesn't change that. I also don't think it's made in Korea anyway.
The limited evidence I have so far for this claim that it is made in South Korea is in the beginning of the game where it stated the provoince where the Zoo is located - a quick google check of its name will show it is a South Korean province.
Other than that I recognize the art style being
reminiscent of other Korean works I've seen before.
It's possible the game is only officially published in Japanese since many anime or hentai culture products from South Korean origin are regularly made in Japanese from the start since they have a larger audience and impact on Japanese speaking/reading target audiences.
If someone can ask the creator if he/she is Japanese or Korean it may be cleared for sure then.
Being aknowledged as a South Korean made game is important to those who want to give the proper credits, and make sure that Korean indie developers aren't overlooked in this industry, just for making their games in Japanese or English, which obviously obscures their origins and artistic heritage.