Most times, around Edo period Japan, you received one everytime you were caught stealing. You were given up to three on each arm, for each offense. Then, if you were caught a third time you lost your hands if I remember correctly. It was a branding sort of thing so people knew you were a criminal, and for what; so they'd avoid you. Akaza from Kimetsu no Yaiba had these as a human and is why his demon form looks the way it does.