This is a cushion cover, pillow cover, towel, or cloth.
Yui Hirasawa from "K-On!" is rockin' out, as always, on this cushion cover! It's made from durable 100-percent cotton, and measures 45 x 45cm; just add a cushion form of the appropriate size, and you've got a comfortable pillow! Please note that the photos shown are of a prototype; the production version may vary.