When the mcdonalds quarter pounder with cheese came out, the europeans came out with this government sponsored measurement for fast food chains to standardize and compete without adopting american standards. (like usb-c over lightning)

;)

I'd never heard of it either. A comment further down suggests it is Japanese.

Digging deeper, the kyu -- or Q for quarter millimeter -- is apparently a foundational distance measurement in Japanese typesetting, which is metric and operates on a millimeter grid.

It's known as the _kyu_ in Japan and used for specifying type (font) sizes.