About: Japanese irregular verbs

Japanese verb conjugation is very regular, as is usual for an agglutinative language, but there are a number of exceptions. The best-known irregular verbs (不規則動詞, fukisoku dōshi) are the common verbs する suru "do" and 来る kuru "come", sometimes categorized as the two Group 3 verbs. As these are the only verbs frequently flagged as significantly irregular, they are sometimes misunderstood to be the only irregular verbs in Japanese. However, there are about a dozen irregular verbs in Japanese, depending on how one counts. The other irregular verbs encountered at the beginning level are ある aru "be (inanimate)" and 行く iku/yuku "go", with the copula behaving similarly to an irregular verb.