Looks like a cleaned up AI generated image.

The yellow in the eyes look off.

QuantumZefir said:

Looks like a cleaned up AI generated image.

The yellow in the eyes look off.

This user's first Pixiv post with Kayoko mentions that they "want to generate images of cute anime girl's feet" so yeah despite missing the tag on Pixiv you're right.

There are also a number of suspiciously machine-like errors in the background, like the uneven beams in the upper-middle area, the partially melted curtain rings, and the multiple metal pipes on the back of her chair plus whatever is going on with the desks behind her.

Unknown009 said:

This user's first Pixiv post with Kayoko mentions that they "want to generate images of cute anime girl's feet" so yeah despite missing the tag on Pixiv you're right.

I completely missed that Pixiv description. Thanks for pointing that out.