This article explores the history, prevalence, causes and effects of incest in Japan. It is illegal in Japan, but still occurs due to traditional attitudes towards marriage, lack of education on the issue, social isolation, mental health issues and power dynamics. Incest can have serious consequences for both parties involved such as physical harm from STDs, psychological harm from guilt or shame, legal repercussions and social ostracism. To prevent incest in Japan, individuals should educate themselves on the issue, seek mental health support if needed and establish supportive networks outside their family.