Just when you thought erasers couldn't get any cuter than a transforming Mt. Fuji eraser, Japanese creative designer Yu (@yuu99jp7) may have set a new standard.

Yu created another type of "transforming" eraser in the form of onigiri (rice balls), one of Japan's favorite snacks. With each mistake you make, the square erasers gradually smooth out into round rice balls, and even reveal their filling!

The delightful erasers are cute enough to begin with, but are designed so that as one uses them, they round out into their usual ball shape and eventually whittle down to show the filling they have inside.

Unfortunately, these are just one of many personal designs Yu makes, and so they are not for sale. Be sure to follow Yu on Twitter and Instagram for even more amazing designs, including insect-inspired chocolate and goldfish swimming pools!