There’s some good stand up comedy material in Japanese shoe measurements:
“Foot Morphology and Fitting of the Shoe to the Foot”
In the Japanese shoe size system, shoe size is determined by length and ball girth. The shoe size indicates the size of the foot that fits the shoe, not the size of shoe itself.
A shoe is manufactured on a last, so last size and shape determines the size and shape of the shoe.
The foot shape may vary even when the foot length is the same. Any shape mismatch causes disuncomfort [sic]. Through research into the size and shape variations of Japanese feet, we are developing a method of shoe design that takes shape characteristics into consideration.