Normally doctors, who went to the war fronts as noncombatants ("kinsoi" or surgeons), shaved their head in order to avoid being shot by mistake; hence, men without a hair were recognized either as a doctor or as a monk in the Edo period.
本来、医者は非戦闘員（金創医）として戦場に出るため、誤射を防ぐ目的で髪を剃り上げていたので、江戸の人々は無髪の頭を見れば医者か僧とわかった。