Japanese Verb Groups and Basic Conjugation

Mastering verb conjugation is the key to unlocking Japanese sentences. It allows you to express time, politeness, and connect ideas. While it may seem daunting at first, Japanese verbs follow remarkably consistent patterns once you learn to categorize them correctly.

The Three Verb Groups: Your Roadmap

Every Japanese verb belongs to one of three categories: u-verbs, ru-verbs, and irregular verbs. The dictionary form of a verb is its plain, present-tense form, like 行く (iku, to go) or 食べる (taberu, to eat). Your first and most crucial task is learning to identify which group a verb belongs to, as this determines its conjugation pattern.

Ru-verbs are the easiest to spot. In their dictionary form, they end in -eru or -iru. For example: 食べる (taberu, to eat), 見る (miru, to see), 起きる (okiru, to wake up). A vital caution: not all verbs ending in -iru or -eru are ru-verbs. Some are u-verbs, like 帰る (kaeru, to return) and 知る (shiru, to know). You must memorize these common exceptions.

U-verbs encompass most verbs in the language. In dictionary form, they end in any u-sound syllable: -u, -ku, -gu, -su, -tsu, -nu, -bu, -mu, or -ru (but not the -eru/-iru pattern of true ru-verbs). Examples include 書く (kaku, to write), 話す (hanasu, to speak), 飲む (nomu, to drink), and the exception 帰る (kaeru, to return).

Irregular verbs have only two common members: する (suru, to do) and 来る (kuru, to come). They are called irregular because they do not follow the standard patterns of the other groups. You must memorize their conjugations individually.

Present Tense and Politeness: The Masu-Form

The masu-form is the standard polite form used in daily conversation with non-intimate acquaintances, in public, and in writing. To conjugate, you first identify the verb's group and follow its rule.

For ru-verbs, simply drop the final る (ru) and add ます (masu). 食べる (taberu) → 食べます (tabemasu) 見る (miru) → 見ます (mimasu)

For u-verbs, change the final u-sound syllable to its corresponding i-sound syllable, then add ます. 書く (kaku, -ku → -ki) → 書きます (kakimasu) 話す (hanasu, -su → -shi) → 話します (hanashimasu) 飲む (nomu, -mu → -mi) → 飲みます (nomimasu)

For irregular verbs, memorize: する (suru) → します (shimasu) 来る (kuru) → 来ます (kimasu)

The negative polite form (present tense "do not...") replaces ます with ません. 食べます → 食べません (tabemasen) 書きます → 書きません (kakimasen) します → しません (shimasen)

Creating Negatives: The Nai-Form

The nai-form creates the plain, present-tense negative ("don't do"). It's also the foundation for other useful forms.

For ru-verbs, drop る and add ない. 食べる → 食べない (tabenai) 見る → 見ない (minai)

For u-verbs, change the final u-sound syllable to the corresponding a-sound syllable, then add ない. 書く (-ku → -ka) → 書かない (kakanai) 話す (-su → -sa) → 話さない (hanasanai) A special case: Verbs ending in -う (like 買う, kau, to buy) change to -わ: 買わない (kawanai).

For irregular verbs: する → しない (shinai) 来る → 来ない (konai)

Talking About the Past: The Ta-Form

The ta-form expresses the plain past tense ("did"). Its conjugation pattern is almost identical to the te-form, which is used for connecting sentences and making requests.

For ru-verbs, drop る and add た. 食べる → 食べた (tabeta) 見る → 見た (mita)

For u-verbs, the ending change follows specific sound rules:

1. If the verb ends in -う, -つ, -る: Replace with った.

買う (kau) → 買った (katta) 待つ (matsu, to wait) → 待った (matta)

1. If it ends in -む, -ぶ, -ぬ: Replace with んだ.

飲む (nomu) → 飲んだ (nonda) 遊ぶ (asobu, to play) → 遊んだ (asonda)

1. If it ends in -く: Replace with いた.

書く (kaku) → 書いた (kaita) Exception: 行く (iku, to go) → 行った (itta).

1. If it ends in -ぐ: Replace with いだ.

泳ぐ (oyogu, to swim) → 泳いだ (oyoida)

1. If it ends in -す: Replace with した.

話す (hanasu) → 話した (hanashita)

For irregular verbs: する → した (shita) 来る → 来た (kita)

To make the polite past tense, change the ます in the masu-form to ました. 食べます → 食べました (tabemashita) 書きます → 書きました (kakimashita) します → しました (shimashita)

Connecting Actions: The Te-Form

The te-form is incredibly versatile, used for connecting sequential actions ("and then"), making requests (with ください), and expressing ongoing states. Its conjugation is identical to the ta-form, but the final た or だ becomes て or で.

Examples from the rules above: 買う → 買って (katte) 待つ → 待って (matte) 飲む → 飲んで (nonde) 書く → 書いて (kaite) 行く → 行って (itte) 泳ぐ → 泳いで (oyoide) 話す → 話して (hanashite) 食べる → 食べて (tabete) する → して (shite) 来る → 来て (kite)

You can use it to make a polite request: 書いてください (kaite kudasai, "Please write").

Common Pitfalls

Misclassifying Ru-Verbs and U-Verbs. The most frequent error is assuming every verb ending in -iru or -eru is a ru-verb. Always double-check common exceptions like 帰る (kaeru - u-verb), 知る (shiru - u-verb), and 入る (hairu, to enter - u-verb). When in doubt, look it up; pattern recognition improves with exposure.

Forgetting the Irregular Conjugations. Because there are only two main irregular verbs, learners sometimes neglect to fully memorize them. Drill する and 来る separately. Remember: する becomes shi- (します、しない、した), and 来る becomes ki- or ko- (来ます、来ない、来た).

Applying U-Verb Rules to Ru-Verbs. A ru-verb like 食べる is conjugated by simply removing る. A common mistake is to incorrectly change the stem before adding the ending, as you would with a u-verb. You do not say 食べきます; the correct polite form is 食べます.

Mixing Up Te-Form and Ta-Form Sound Changes. The sound changes for u-verbs (e.g., $む\to んで$) are tricky. A useful strategy is to learn the ta-form thoroughly first. Once you can reliably produce 飲んだ (nonda), converting it to the te-form 飲んで (nonde) becomes simple.

Summary

• Japanese verbs are systematically categorized into u-verbs, ru-verbs, and the irregular verbs する and 来る. Correct identification is the essential first step to conjugation.
• The masu-form is the standard polite present tense, created by modifying the verb's ending to an -i sound (for u-verbs) or dropping -る (for ru-verbs) and adding ます.
• The nai-form creates plain negatives, while the ta-form expresses the plain past tense. The te-form is used for connecting sentences and making requests.
• U-verbs undergo specific sound changes (e.g., $つ\to った$, $む\to んだ$) for the ta-form and te-form, which must be memorized as a set of patterns.
• Always be cautious of common u-verbs that look like ru-verbs, such as 帰る and 知る, and dedicate time to memorizing the unique conjugations of する and 来る.