How to form past and present for ru-verbs and u-verbs
To form the past and present tenses for ru-verbs and u-verbs in Japanese, the key difference is that ru-verbs stay almost unchanged before the ending, while u-verbs change their final sound before conjugation. In both groups, the plain form is the dictionary form, and the polite form is built with ます or ました.
Ru-verbs (Ichidan verbs)
- Present (dictionary/plain form): The verb ends in る (ru), e.g., 食べる (taberu) “to eat”.
- Present polite form: Drop the る and add ます, e.g., 食べます (tabemasu).
- Past (plain form): Drop the る and add た, e.g., 食べた (tabeta).
- Past polite form: Drop the る and add ました, e.g., 食べました (tabemashita).
Ru-verbs are also called ichidan verbs because they belong to one regular conjugation pattern. The stem is usually the part before る, so 食べる becomes 食べ- in every basic tense: 食べます, 食べた, 食べました. Common examples include 見る (miru, “to see/watch”) → 見ます, 見た, 見ました, and 起きる (okiru, “to wake up”) → 起きます, 起きた, 起きました.
A common mistake is assuming every verb ending in る is a ru-verb. That is not true. Japanese has many u-verbs that also end in る, such as 走る (hashiru, “to run”), 帰る (kaeru, “to return”), and 切る (kiru, “to cut”). These do not follow the ru-verb pattern, so the final sound must be checked rather than the spelling alone.
U-verbs (Godan verbs)
- Present (dictionary/plain form): The verb ends in a u vowel sound (except ru verbs that are ru-verbs), e.g., 読む (yomu) “to read”.
- Present polite form: Change the final u-vowel sound to its corresponding i-vowel sound and add ます, e.g., 読みます (yomimasu).
- Past (plain form): The past tense varies depending on the final syllable but often ends in った, んだ, いた, or った, e.g., 読んだ (yonda).
- Past polite form: Change the final u-vowel sound to i-vowel and add ました, e.g., 読みました (yomimashita).
U-verbs are called godan verbs because the final kana shifts across five vowel rows in conjugation. The change before ます is mechanical: 読む becomes 読みます, 書く becomes 書きます, 話す becomes 話します, and 泳ぐ becomes 泳ぎます. The plain past form is less regular, but the pattern is predictable once the verb ending is known.
A useful way to think about godan verbs is to memorize the past-tense sound groups:
- -う, -つ, -る → -った: 買う (kau) → 買った, 待つ (matsu) → 待った, 帰る (kaeru) → 帰った
- -む, -ぶ, -ぬ → -んだ: 読む (yomu) → 読んだ, 遊ぶ (asobu) → 遊んだ, 死ぬ (shinu) → 死んだ
- -く → -いた: 書く (kaku) → 書いた
- -ぐ → -いだ: 泳ぐ (oyogu) → 泳いだ
- -す → -した: 話す (hanasu) → 話した
The polite past is much simpler than the plain past. Once the verb changes to the i-stem, ます becomes ました: 書きます → 書きました, 話します → 話しました, 泳ぎます → 泳ぎました. In everyday conversation, the polite forms are often easier to produce quickly because the conjugation pattern is stable across both ru-verbs and u-verbs.
Quick comparison
- Ru-verb: 食べる → 食べます / 食べた / 食べました
- U-verb: 読む → 読みます / 読んだ / 読みました
This distinction is fundamental in Japanese verb conjugation. 1, 2, 7, 9, 10
Practical speaking pattern
In real conversation, tense choice usually depends on whether the sentence is in plain style or polite style. The plain past is common in casual speech, narration, and stories, while the polite past is common in neutral speaking situations, introductions, and service contexts. Recognizing the verb type quickly is especially useful in listening, because the difference between 読みます and 読みました, or 食べます and 食べました, signals whether the action is present/future or completed.