I'm not the best at discerning AI art, and nothing really jumped out at me here but the overall look just seemed a little suspicious. Looking at the Pixiv account, posts from just earlier this month seem to have a drastically different/more unrefined style.

NinjaPope said:

I'm not the best at discerning AI art, and nothing really jumped out at me here but the overall look just seemed a little suspicious. Looking at the Pixiv account, posts from just earlier this month seem to have a drastically different/more unrefined style.

I think this person traces AI art judging off their shaky lines and other pixiv submissions- they overcorrect it to the point of it looking somewhat natural but there are still signs they don't really know what they're doing since they seem to be a novice artist. The AI signs are more obvious on their shiroko (blue archive) post.

m4rs said:

I think this person traces AI art judging off their shaky lines and other pixiv submissions- they overcorrect it to the point of it looking somewhat natural but there are still signs they don't really know what they're doing since they seem to be a novice artist. The AI signs are more obvious on their shiroko (blue archive) post.

This seems to be the best interpretation, it's definitely AI-Assisted with something like this. The Karin piece they have on their pixiv has some pretty obvious signs too; bad shading, and bizarre hand forms that a regular artist would have corrected if they had sketched it themselves.

One other tell with this piece in particular, is that Illustrious' hat being a small as it appears to be here is a pretty common hallmark of generated Illustrious images. Most models seem to struggle with stylized hats like this in general, so it can be useful for picking out something that's been generated if you're familiar with the character.