Japanese verb groups: dictionary forms and polite endings

食べる and 帰る both end in る. Conjugate them the same way and one comes out wrong: 食べる politely becomes 食べます, but 帰る becomes 帰ります, not 帰えます, the form its ending would predict. The difference is which of Japanese's two verb groups each one actually belongs to, and that single fact decides how a verb builds every other form you will need, starting with the polite ます ending most beginners meet first.

Every verb has to be sorted into one of these groups before you can conjugate it at all, and the sorting is not always obvious from spelling. Get it wrong and every later form (the negative, the past, the て-form) inherits the mistake. Get it right at the dictionary form, and the rest of conjugation is pattern-matching.

Two groups decide almost every conjugation

A verb's dictionary form (its plain, unconjugated, listed-in-a-dictionary shape) always ends in an う-row sound: う, く, ぐ, す, つ, ぬ, ぶ, む or る. That single fact splits nearly the whole language into two working groups.

• う-verbs (also called godan, "five-step"): the ending changes before most endings attach. 飲む, 書く, 話す, 待つ, 会う are う-verbs.
• る-verbs (also called ichidan, "one-step"): the ending barely changes at all. 食べる, 見る, 起きる, 寝る are る-verbs.

A third, tiny group sits outside both patterns. する (to do) and 来る, kuru (to come) are Japanese's only two irregular verbs, and their forms (します, 来ます) are memorised individually rather than built from either rule. Everything else you will meet is one of the two groups above.

Ending in る doesn't mean what it looks like

Here is the part spelling alone will not tell you. Both groups can produce a dictionary form ending in る, so that ending by itself does not sort a verb. You need one more test: the sound immediately before る.

Sound before る	Group	Example
あ, う, お	う-verb, always	作る (つくる), 乗る (のる)
い, え	る-verb (usually)	食べる, 見る, 起きる

"Usually" is doing real work in that second row. A short, fixed list of common verbs end in an い or え sound before る and still conjugate as う-verbs:

Verb	Reading	Meaning
帰る	かえる	to go home
入る	はいる	to enter
走る	はしる	to run
知る	しる	to know
要る	いる	to need
切る	きる	to cut
喋る	しゃべる	to chat
減る	へる	to decrease

None of these are rare verbs you can afford to guess at. 帰る and 知る are two of the first hundred verbs any beginner meets. There is no shortcut for this list beyond meeting each one enough times that the correct form stops requiring a check.

That is exactly the kind of thing a rule cannot give you and repetition can. When you meet one of these verbs somewhere real (a caption, a line in a show, something a friend says), capturing the sentence in Kikusho keeps 帰ります in the exact context you met it, reading and example sentence intact, instead of a bare headword you have to reconjugate from memory each time it comes up again.

Each group turns into ます a different way

For an る-verb, drop る and add ます: 食べる → 食べます, 見る → 見ます. There is nothing else to remember.

For an う-verb, the final kana's u-sound changes to the matching i-sound, and ます attaches to that:

Ending	Becomes	Example	ます form
う	い	会う	会います
く	き	書く	書きます
ぐ	ぎ	泳ぐ	泳ぎます
す	し	話す	話します
つ	ち	待つ	待ちます
ぬ	に	死ぬ	死にます
ぶ	び	遊ぶ	遊びます
む	み	飲む	飲みます
る	り	帰る	帰ります

死ぬ is worth noticing on its own: it is the only verb in the language ending in ぬ, so that whole row exists for one word. The last row is the exception verb from above, conjugating exactly like any other う-verb once you know which group it is in.

する and 来る sit outside this table entirely: します and 来ます (きます) are simply learned as themselves.

The dictionary form isn't a half-built sentence

It is easy to treat 食べる as raw material (the thing you conjugate) and ます as the finished product. It isn't. 食べる is a complete sentence on its own, meaning "I eat" or "I'll eat," in exactly the register you would use with a friend, a sibling, or in your own head. ます is not what makes a verb usable; it is what makes it polite.

The choice between them is about who is listening, not about which one is more correct. Service staff, a stranger, a work presentation: ます. A friend, a parent, a diary entry, your own thoughts: the dictionary form, unconjugated. Most textbooks teach ます first because getting the register wrong with a stranger reads worse than getting it wrong with a friend. But the plain form is not a beginner shortcut you graduate out of. It is also the base that most other grammar (と, けど, つもり, plain-form quoting) attaches to directly, which is one reason it keeps reappearing long after ます stops being new.

The mistake that gives away a beginner's ear

The tell is almost always the exception list, in one of two directions. Either a real う-verb gets treated like a る-verb because it ends in -eru or -iru (帰えます instead of 帰ります, 知えます instead of 知ります), or, less often, an ordinary う-verb gets ます glued straight onto its dictionary form with no vowel shift at all (飲むます instead of 飲みます). Both are audible to a native speaker the instant they land, in a way a wrong particle sometimes isn't, because the ending is not approximately right. It is a different verb's ending.

Three sentences to check the rule against

Question 1. Which is the correct ます form of 飲む (to drink)?

a) 飲みます b) 飲むます c) 飲びます d) 飲ぬます

Answer 1: 飲みます. 飲む is an う-verb ending in む, and む's い-row equivalent is み: む becomes み before ます. (b) skips the vowel shift entirely; (c) and (d) shift to the wrong row, ぶ and ぬ instead of む.

Question 2. Put these into a natural sentence meaning "I'll go home at seven": 家に ・ 帰ります ・ 七時に ・ 私は

Answer 2: 私は七時に家に帰ります。 Topic first (私は), then time (七時に), then the place marked with に (家に), verb last (帰ります). 帰る keeps its う-verb ます form despite the -eru ending, the exception covered above, now in the sentence where it shows up.

Question 3. Complete the message with the right form of 会う (to meet): 「あした、ともだちと えきで＿＿＿。」(Tomorrow, I'll ___ my friend at the station.)

a) 会います b) 会うます c) 会えます d) 会いります

Answer 3: 会います. 会う is an う-verb; う becomes い before ます. (c) 会えます is the potential form ("can meet"): a different meaning, not a spelling slip. (b) and (d) do not shift the vowel correctly.

Once these two groups and their exceptions stop needing a table, the rest of conjugation moves fast: the negative, the past and the て-form all reuse the same split, which is also where Japanese's politeness system starts, not with keigo, but with the plain-versus-ます choice this lesson covers.