I believe this was made using Koikatsu by applying the right screen filters and editing it afterwards. Which does go to show how much potential Koikatsu really has as a content creation tool
I want to make a few comments on this work as an editor.
First off, it's clear that this is a non-Japanese artist making a manga-style comic with Koi. What's impressive about this that sets it apart from other Koi or 3D comics is that there is a subtle but very devoted attention to detail in emulating the manga style. This goes beyond the greyscale filter and left-right reading order; it's the panel layout, it's the posing of the characters, it's the orientation of the bubbles (Vertical bubbles! Vertical SFX bubbles! Purposefully done with horizontal SFX text!!!)
There are tons of 3D comics on this site. Many made with Koikatsu too. A lot of them are just static 16:9 screenshots/renders with text plastered over them. Some of them probably aren't *bad* story-wise, but the fundamental issue they face is how unnatural it feels to read (at least, from the POV of a person whose bread and butter is manga and doujinshi). With this, that fundamental issue is completely bypassed, and the result is a Koikatsu-made manga that's elevated above the others because of this stylistic decision.
I didn't know you can get this kind of fidelity out of Koikatsu, but after seeing this, I'll admit. I'm very impressed.