The term that readily comes to mind is "nishoku" (二色) which literally means "two colors." The kanji compound can also be read "futashoku." I'm sure there are other terms which may work, but that's the one that comes to my mind most readily.
In Kojiki, the Chamberlain translation speaks of Susanowo dropping a flayed "piebald horse" into the weaving hall of the sun goddess, which is what causes her to shut her self up behind the rock door of heaven. Pinto and piebald are the same type of horse.
The kanji used in Kojiki is 斑 and more modernly either pronounced buchi or as fuiri (斑入り). That's the most traditional reference for what you want, I think.