Japanese Plain Negative Form (~nai)

The plain negative form of Japanese verbs ends in ~nai. For Group 1 (U-verbs), change the final 'u' sound to its corresponding 'a' row sound and add ~nai (e.g., iku -> ikanai). If the verb ends in 'u' (like kau), change it to 'wa' (kau -> kawanai). For Group 2 (Ru-verbs), drop the final ~ru and add ~nai (e.g., taberu -> tabenai). Group 3 verbs are irregular: suru -> shinai, kuru -> konai. The verb 'aru' (to be) is uniquely replaced entirely by 'nai'.