Okay, this artist is confusing me. This particular image was from the Pixiv account, while post #180164 is from the artist's homepage. The only difference between the two images is the width; instead of them being a matter of cropping, however, they differ in their actual proportions.
My eyes tell me that this is the "correct" image, but I'm not positive - I'm simply baffled at how something like this can occur from a single source. It's not a singular event, either, as the previous Tewi image I've uploaded from this artist had the same deal: Pixiv account image was a bit less width, homepage was wider and appears to be the "stretched" version.