Japanese Verb Groups Explained: U-verbs, Ru-verbs, and Irregular Verbs (Complete Guide)

Before you can conjugate a single Japanese verb, you need to know one thing: which group does this verb belong to? Japanese verbs fall into three groups, and the group determines how you form the te-form, nai-form, passive, potential, and every other conjugation. Get this foundation right, and all other grammar becomes much easier. Skip it, and you’ll make conjugation errors for years.

*Group 1 can also end in -ru — this is the main source of confusion for learners. Keep reading for the rules.

Group 1: U-verbs (Godan Verbs / 五段動詞)

U-verbs are the largest group. Their dictionary form ends in one of these sounds from the u row of the hiragana chart: u, ku, gu, su, tsu, nu, bu, mu, ru. When you conjugate them, the final syllable changes — it shifts to a different row (a, i, e, o) depending on the form you need.

Notice: 帰る (kaeru) ends in -ru but is a U-verb! This is explained in detail below.

Group 2: Ru-verbs (Ichidan Verbs / 一段動詞)

Ru-verbs always end in -eru or -iru. When you conjugate them, you simply drop the -ru and add the ending. The stem never changes — that’s why they’re called ichidan (one-level) verbs.

Yuka

The easiest way to remember ru-verb conjugation: just drop the る and add what you need. 食べる → 食べ + て = 食べて. 見る → 見 + ない = 見ない. The stem (食べ / 見) never changes, so once you know the stem, all forms are easy!

Group 3: Irregular Verbs — する and 来る

Only two truly irregular verbs exist in Japanese: する (to do) and 来る (kuru, to come). You simply need to memorize their forms — there are no patterns to follow.

Good news for learners: Any verb ending in -suru (勉強する, 運動する, etc.) follows する conjugation. There are hundreds of these compound verbs, and they all work identically to する.

The Hardest Part: Ru-ending U-verbs (The Trap)

The trickiest thing in Japanese verb groups is that some U-verbs end in -ru. These verbs look like ru-verbs but conjugate as U-verbs. You cannot tell them apart just from the dictionary form spelling — you have to recognize the common ones.

The rule: If the syllable before -ru is not an -e sound or -i sound, it is almost certainly a U-verb. But if it IS an -e or -i sound, it could be either — you need to memorize.

Practical tip: When you learn a new -ru verb, also learn its te-form immediately. If the te-form ends in -tte (って), it’s a U-verb. If it ends in -te (て) with no doubling, it’s a ru-verb.

Rei

A helpful shortcut: if a verb ends in -aru, -oru, or -uru (not -eru or -iru), it is ALWAYS a U-verb. No exceptions. And if it ends in -eru or -iru, you need to check — most are ru-verbs, but the exceptions (帰る, 切る, 走る, etc.) come up all the time.

How Verb Groups Affect Every Conjugation

Once you know the group, all conjugations follow clear patterns. Here’s a side-by-side comparison using one verb from each group:

Decision Flowchart: What Group Is This Verb?

Is the verb する or 来る?
    |
    YES --> Group 3 (Irregular) -- memorize all forms
    |
    NO --> Does the dictionary form end in -ru?
                |
                YES --> Does the syllable BEFORE -ru end in an -e or -i sound?
                            |
                            YES --> Is it one of the known U-verb exceptions?
                                    (帰る, 切る, 走る, 知る, 入る, 要る, 滑る, etc.)
                                        |
                                        YES --> Group 1 (U-verb)
                                        |
                                        NO  --> Group 2 (Ru-verb) -- probably safe
                            |
                            NO  --> Group 1 (U-verb) -- always
                                    (ends in -aru, -oru, -uru = always U-verb)
                |
                NO  --> Group 1 (U-verb) -- ends in -ku, -gu, -su, -tsu, -nu, -bu, -mu

Quick Quiz: Identify the Verb Group

Look at each verb and decide: Group 1 (U-verb), Group 2 (Ru-verb), or Group 3 (Irregular)?

Q1. 飲む (nomu) — to drink

▼ Answer: Group 1 (U-verb) — ends in -mu. Te-form: 飲んで

Q2. 起きる (okiru) — to wake up

▼ Answer: Group 2 (Ru-verb) — ends in -iru, no exceptions. Te-form: 起きて

Q3. 切る (kiru) — to cut

▼ Answer: Group 1 (U-verb) — common exception! Ends in -iru but is a U-verb. Te-form: 切って (not 切れて)

Q4. 来る (kuru) — to come

▼ Answer: Group 3 (Irregular) — one of only two irregulars. Te-form: 来て (kite)

Q5. 泳ぐ (oyogu) — to swim

▼ Answer: Group 1 (U-verb) — ends in -gu. Te-form: 泳いで

Q6. 寝る (neru) — to sleep

▼ Answer: Group 2 (Ru-verb) — ends in -eru, standard ru-verb. Te-form: 寝て

Which verb group trips you up most? Tell me in the comments — especially if you found a tricky U-verb that ends in -ru!

Ready to practice conjugation with a real tutor? Book a Japanese lesson on italki — drilling verb groups with a native teacher is the fastest way to make these patterns automatic.

Keep Learning

Now that you know the verb groups, apply them to these essential conjugations:

あわせて読みたい

Te-Form Japanese: 10 Uses Every Learner Must Know Master the Japanese te-form: conjugation rules for all verb groups plus 10 essential uses including requests, ongoing actions, permission, and more.

あわせて読みたい

Nai-Form Japanese: How to Make Any Verb Negative Learn the Japanese nai-form (ない form) for all three verb groups. Covers negative present, past, requests (ないでください), obligation, and permission patterns.

あわせて読みたい

Japanese Potential Form: られる vs できる (Can You…?) Learn how to say 'can' in Japanese using the potential form られる/れる and できる. Includes conjugation rules, particle shift (を→が), and ら抜き explained.