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I have been wondering for a long time which anime this is from.
This isn't from an anime. It's original art by this Pixiv user (warning, may be a bit NSFW) for her FC2 blog (also maybe not safe for work).
The characters in the image are:
(All below links are possibly NSFW.)
A larger version of this image can be found on Danbooru. Apparently, this image is just a drawing by an artist named Naomi as part of her 世界の果ての喫茶店 (Cafe at the End of the World) series.