The plain negative form is the casual “do not” form. It is made with the ない-form and is used in informal speech and in many grammar patterns. Key points: • Plain negative uses ない: 行かない, 食べない • Used in casual speech and before other grammar • Equivalent to ません in polite speech • Time words show present or future negative For example, “今日は行かない” means “I am not going today.” “肉は食べない” means “I do not eat meat.” The ない-form is a key base form. Many other patterns use it (e.g., 〜なくてはいけない). So learning the plain negative helps you build many other structures. Be careful with verb group changes: 行く → 行かない, 飲む → 飲まない, 食べる → 食べない, する → しない, 来る → こない. Even if you mostly speak politely, understanding the plain negative helps you understand casual speech and grammar patterns.