This chapter surveys how impoliteness, broadly conceived, is approached and studied in Japan. It first gives a brief historical sketch of how impoliteness research has been marginalized and neglected among Japanese linguists, as opposed to accumulated research on politeness. The chapter then reviews selective areas in impoliteness research, beginning with pioneering lexical work in the first section. The second section discusses early descriptive studies and research utilizing the Japanese conceptual/analytical framework of taigū hyōgen, or treatment expressions. In light of the increasing use of digital technology, impoliteness via online platforms is examined in the third section, specifically case studies in cyberbullying and domestic violence reported by female victims on social media. Turning to the norms of impoliteness in communities of practice, the fourth section focuses on two different contexts, parliamentary debates and online discussion forums, which reveals that impoliteness occurs when respective community norms are violated. From the perspective of cultural anthropology, two phenomena unique to the Japanese context are described in the fifth section. One is the language behavior of Japanese idols and their fans in subcultural communities, where apparently rude language functions in potentially positive ways. The other is a “Curse Festival”, where participants are encouraged to yell rude things at mythical beings. The addition of these anthropological approaches to impoliteness broadens the scope of impoliteness research in Japan. This chapter is intended to help readers better understand how impoliteness has been approached and studied in Japan, which provides insight into the current trends and points toward future directions for research both local and global.