It's hard to find the model used for images that are uploaded from Twitter/Pixiv unless the artist has specified it in their page/it's a self upload, or if the metadata is included.
The metadata here does exist but I can't find anything about a model called "Chiruchiru7" so it might as well just be a private model. But anyway, keep in mind that the uploader who uploaded a Pixiv/Twitter image most likely won't have an idea of the model used unless they already added it.
