I had recently come across a
particular image wilst browsing Gelbooru, and after examining the final panel, determined this must be a form of development, as opposed to stuffing a creature in her shirt.
Unfortunately it was taken off Danbooru, and the respective Pixiv user's account has been deleted.. which is a shame, as there was mention of a follow-up image on his account, as evidenced by the
residual posts on Danbooru.
This is the (currently expired) link to the Pixiv account, and searches in IQDB and TinEye have no results, unfortunately.
I had attempted to translate the remainder of the text on the image, with minor success. (as the translation doesn't appear on gelbooru to my knowledge) in the attached text document, if anyone is interested.