Japanese Verb Groups: Ichidan, Godan and the Two Irregulars Explained

The three groups and what they are called

Textbooks use different names for the same three groups. Japanese schools say godan, ichidan and henkaku dōshi; Genki says u-verbs, ru-verbs and irregular verbs; Minna no Nihongo numbers them Group 1, 2 and 3. They are the same split: godan, u-verbs and Group 1 are one thing; ichidan, ru-verbs and Group 2 are another; the irregulars are suru and kuru.

The names describe how the verb changes. Ichidan means one step: the verb has one stem, and you drop ru and attach whatever ending you need. Godan means five steps: the final syllable moves through the five vowels of its kana row, a, i, u, e, o, and each vowel opens a different set of forms. Kaku (to write) becomes kaka (negative), kaki (polite stem), kaku (dictionary), kake (imperative and conditional) and kakō (volitional). That five-vowel movement is the whole engine of godan conjugation.

Sorting a verb in three questions

Here is a method that sorts any verb in a few seconds. First, is it suru, kuru or a compound with suru such as benkyō suru? If so, it is irregular. Second, does the dictionary form end in iru or eru, that is, does the syllable before the final ru carry an i or e vowel? If not, it is godan: kau, kaku, hanasu, matsu, shinu, yomu, asobu, toru and all verbs ending in aru, uru and oru are godan without exception. Third, if the verb does end in iru or eru, it is ichidan unless it is on the exception list.

Only the third question needs memory. Roughly nine out of ten iru and eru verbs are ichidan: taberu, miru, okiru, neru, deru, kariru, oshieru, wasureru, akeru. The godan minority are common verbs, which is why they cause trouble: you meet kaeru and hairu in your first month. Learn those as a small set and the rule covers everything else.

The iru and eru exceptions worth memorising

The safest way to hold the exceptions is to learn them with their negative form, because the negative shows the group at once: kaeranai, not kaerenai. Here are the exceptions a learner meets in the first year, with a short example for each.

Two pairs deserve special care because the same sound belongs to both groups. Kiru meaning to wear is ichidan, kinai, kimasu; kiru meaning to cut is godan, kiranai, kirimasu. Iru meaning to be is ichidan, inai, imasu; iru meaning to need is godan, iranai, irimasu. Kanji separates them in writing, 着る and 切る, いる and 要る, but in speech only context does, so learn each with a sentence.

Suru and kuru: the two irregulars

Suru, to do, and kuru, to come, do not follow either pattern, so their forms are memorised as a set. Suru has the stem shi for most forms, shinai, shimasu, shite, shita, and the special forms dekiru for potential, shiyō for volitional, sureba for conditional and shiro or seyo for the imperative. Kuru changes its vowel in the stem: konai, kimasu, kite, kita, korareru, koyō, kureba, koi. The kanji 来 stays the same while the reading moves between ku, ki and ko, which is why kuru is best learned by ear.

Suru matters far beyond one verb, because thousands of nouns become verbs by adding it: benkyō suru, denwa suru, ryōri suru, yoyaku suru, and all of them conjugate exactly like suru, which makes it the highest-value verb table in the language. Kuru appears in compounds such as motte kuru (to bring) and tsurete kuru (to bring someone along), where only the kuru part changes.

One verb, three groups: the comparison chart

The chart below puts a representative verb from each group side by side. Taberu stands for ichidan, kaku for godan, and suru and kuru for the irregulars. Read across each row and the pattern becomes visible: ichidan swaps ru for the ending, godan moves the vowel first and then attaches the ending, and the irregulars change their stem.

Notice that the ichidan potential and passive are identical, taberareru. In casual speech many people shorten the potential to tabereru; that ra-nuki form is widespread but non-standard in exams and formal writing, so produce the full form and recognise the short one.

Why the group decides every form

Learners sometimes ask whether they can skip the sorting and learn each conjugated form as vocabulary. It does not scale, because every new verb would need six or seven entries. Knowing the group turns each verb into one entry plus a pattern, and lets you conjugate verbs you have never seen: if a verb ends in su, its negative ends in sanai and its past in shita.

The group also decides the te form, the form you use most in speech. Ichidan te form is te after the stem: tabete, mite, okite. Godan te form depends on the final syllable: u, tsu and ru become tte; mu, bu and nu become nde; ku becomes ite, gu becomes ide, su becomes shite. A learner who thinks kaeru is ichidan says kaete, which is a different verb, to change, instead of kaette. Errors like that are why sorting comes first.

A ten-minute drill routine

Sorting becomes automatic through short daily rounds rather than long sessions. The routine below takes about ten minutes. Say every answer out loud, because the mouth remembers what the eye forgets.

• Minute one to two: read twenty dictionary forms and call the group for each, aiming for under two seconds per verb
• Minute three to four: for the same twenty, say the plain negative, which exposes any mis-sorted verb immediately
• Minute five to six: say the te form for each, listening for tte, nde, ite and shite on the godan verbs
• Minute seven to eight: run the exception list in negative and past, then conjugate suru and kuru without pausing
• Minute nine to ten: build six sentences about your day using at least two verbs from each group

Rotate the twenty verbs every few days. After two or three weeks the group question stops being a question, and you will produce negatives and te forms without noticing which pattern you used.

Common mistakes and how to fix them

The first mistake is treating every iru and eru verb as ichidan, which produces kaerenai, hairenai and shirenai. The fix is the exception list drilled with negatives until the wrong forms sound odd. The second mistake is the reverse, treating true ichidan verbs as godan and saying tabaranai or miranai. If a verb ends in iru or eru and is not on your exception list, trust the rule and drop the ru.

The third mistake is mixing up godan te forms, yonde versus yomite or kaite versus kakute; the te form follows the final syllable, so group verbs by their last kana when you drill. The fourth is letting suru compounds drift into godan patterns, for example benkyō suranai. The last is confusing the kiru and iru homophones, which only sentences can fix: learn kōto o kimasu next to yasai o kirimasu, and tomodachi ga imasu next to fukuro wa irimasen.