we all asked how his name was made and Yoshitomi came up with the best way this name was made take a look xD
Yoshitomi 2 min ago
I bet the "Human Mustard" origin is a child's dream to be half human, half mustard.
Once the child learned this dream was impossible, he cried mustardy tears.
And thus, he created HUmanMustard, with the capital U to celebrate the union of the two entities.