What is Kunihiro?
1.
Unwanted leftover semen. IE: Semen that is found in unwanted areas after a sexual act. Be it masturbation and you leave some on your hands, or you just got with your girl and didn't tell her everywhere you shot, or just some casual encounter in the bathhouse and you forget to clean up.
Guy 1: Man, I just scored with that girl in the bathroom.
Guy 2: Which one? That one that has some kunihiro in her hair?
Guy 1: Hell yeah, I always leave some kunihiro behind.
See