As the person who posted that wallpaper, I apologize that the filename didn't make it easy enough to find, I first heard the title of this manga translated as "The Demon Who Became My Sister!" so I figured the filename I chose would be easily googleable and it would avoid questions about the sauce. I now realize the official English title is completely different ("The Elder Sister-Like One") and that googling sister demon brings up a completely unrelated anime. Apologies have more Chiyo.
I do however agree with >>2092702
use Yandex it is great for finding the sources of anime it and saucenao should be checked before begging for sources. While SauceNao wouldn't help with the one above since it is a cropped version of a larger image, Yandex quickly found it full image plus other pictures of Chiyo. I highly recommend bookmarking them