Danbooru-based image board with a specialization in high-quality images.
mijinkouka wallpaper

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It's from Yakuzaishi Kyoukai no Chikensha Boujuu An'nai [ The Pharmacy Society's Clinical Tester Recruitment Guide / 薬剤師協会の治験者募集案内 ]
Illustrator: Mijinkouka
Moar information here: http://www.kadokawa.co.jp/product/321402000055/