Koro is a mythological belief primarily found in parts of Southeast Asia, particularly in China and India. It describes a condition where a man believes that his genitals are shrinking or retracting into his body, leading to intense anxiety and fear of impotence. This phenomenon is often linked to cultural beliefs about masculinity and virility. The myth of Koro is sometimes associated with mass hysteria, where groups of individuals may experience similar fears simultaneously. In some cases, it has been reported during periods of social stress or anxiety, reflecting the impact of cultural and psychological factors on health perceptions.