***Millions of teachers are telling you "the unkind Japanese that should not be used lightly"!*** Teach you to understand the other side of Japanese culture: "Directly vent, without modification" negative emotions. Almost all textbooks teach "polite and decent" Japanese. But everyone has negative emotions. Watching "Japanese dramas, anime, and variety shows", expressing "complaints, anger, curses, and criticism" is the norm. When learning, we will avoid using "impersonal words", but "impersona