Is this a third party edit? The rest of this artists stuff here is in Japanese and from a different account.
It's first-party. Aside from the fact that that account is older than his main Japanese one and looks completely legit, if you check his Pixiv he directly says he's a foreigner and that Japanese is hard. I did think his art gave a somewhat non-Japanese impression at times, but not strongly enough to place it, and I never cared to check whether that gut feeling was right. In hindsight yeah, Korean makes sense.