This is a cushion cover, pillow cover, towel, or cloth.
This duvet/comforter cover from Key-th features Taihou from "Azur Lane" in her "Seaside Daydreams" illustration! It's made of a fabric that's smooth to the touch, supple, and super-comfortable! It has a zipper on the long side, and there's also a string on the inside that allows you to secure the duvet inside. Order yours today!