Verb Conjugation: Past Tense

Past Tense — Your Second Conjugation

If you've already conquered the present tense, good news: the polite past tense is almost free. You already know the hard part.

The past tense in Japanese covers one thing:

• Completed actions — things that already happened: "I ate sushi" (寿司を食べました)

Unlike the present tense (which doubles as future), the past tense is straightforward in meaning. Something happened. It's done.

The challenge isn't what it means — it's how godan verbs change in the plain form. But we'll get there.

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Polite Past: The Easy Win

If you know the ます form, you already know the polite past. Just swap the ending:

That's it. The stem doesn't change at all. Everything you learned about shifting to the い-row for godan verbs? Same thing. You just replace ます with ました.

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Group 2: Ichidan Verbs (Still Easy)

The Rule

Drop る, add ました or ませんでした. Same stem as present tense.

Polite Past

If you can say 食べます, you can say 食べました. Zero new rules.

Plain Past

Drop る, add た (affirmative) or なかった (negative). The negative is just the present negative ない with its own past form: ない → なかった.

In Practice

昨日寿司を食べました。(Kinō sushi o tabemashita.) "I ate sushi yesterday."

映画を見ませんでした。(Eiga o mimasen deshita.) "I didn't watch the movie."

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Group 1: Godan Verbs (Here's Where It Gets Fun)

Polite Past — No Surprises

The polite past works exactly like ichidan: same い-row stem, just swap ます for ました.

Nothing new here. If you've been using ます form, you already have this.

Plain Past — The Sound Changes

Here's the part that trips people up. The plain past tense of godan verbs doesn't follow the simple vowel-row shifting you've seen so far. Instead, the verb ending transforms based on its final consonant sound.

These are the same sound changes as the te-form (～て), just with た/だ instead of て/で. If you already know the te-form, you already know the plain past.

The Rules: Grouped by Sound Change

Group A: ～った (double っ + た)

Verbs ending in う, つ, る → drop the ending, add った

The っ creates a brief pause before た — listen for it when you hear native speakers.

Group B: ～んだ (ん + だ)

Verbs ending in む, ぶ, ぬ → drop the ending, add んだ

Notice it's だ (voiced), not た. The ん sound naturally leads into a voiced consonant.

Group C: ～いた / ～いだ

Verbs ending in く → drop く, add いた Verbs ending in ぐ → drop ぐ, add いだ (voiced)

Again, ぐ gets the voiced version (だ instead of た).

Group D: ～した

Verbs ending in す → drop す, add した

This one is the cleanest — す just becomes した. Only one pattern to remember.

The One Exception: 行く

行く (iku — to go) is the one godan verb that breaks the く → いた rule:

❌ 行いた (ioita) ✅ 行った (itta)

It follows the っ + た pattern instead. This is the only irregular godan sound change. Just memorize it.

The Memory Trick

There's a famous mnemonic song to the tune of "Santa Claus is Coming to Town":

い・ち・り → った み・び・に → んだ き → いた ぎ → いだ し → した

Or think of it in groups:

• Small tsu group (う, つ, る): the sounds that "stop short" → った
• N group (む, ぶ, ぬ): the sounds made with your lips/nose → んだ
• I group (く, ぐ): the "k" sounds → いた/いだ
• S group (す): hissing sound → した

Plain Past Negative

Good news — the plain past negative is completely regular for all godan verbs. Take the plain negative (あ-row + ない), and turn ない into なかった:

No sound changes. No exceptions. If you can make the ない form, just swap ない → なかった.

In Practice

昨日本を読んだ。(Kinō hon o yonda.) "I read a book yesterday." (casual)

先週友達に会った。(Senshū tomodachi ni atta.) "I met my friend last week." (casual)

写真を撮りました。(Shashin o torimashita.) "I took a photo." (polite)

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Group 3: Irregular Verbs (Still Just Two)

する (suru) — To Do

All する compounds work the same way:

来る (kuru) — To Come

Same reading shifts as present tense:

• ました form: きました (ki-mashita)
• た form: きた (ki-ta)
• なかった form: こなかった (ko-nakatta)

In Practice

昨日たくさん勉強しました。(Kinō takusan benkyō shimashita.) "I studied a lot yesterday."

友達が日本から来た。(Tomodachi ga Nihon kara kita.) "My friend came from Japan."

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The Complete Past Tense Cheat Sheet

Polite Past (ました form)

Plain Past

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Sound Change Summary (Godan Plain Past)

Exception: 行く → 行った (not 行いた)

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Common Mistakes to Avoid

1. Using the wrong sound change

❌ 飲む → 飲った (notta) ✅ 飲む → 飲んだ (nonda)

む-ending verbs go to んだ, not った. Drill the groups until they're automatic.

2. Forgetting 行く is irregular

❌ 行く → 行いた (ioita) ✅ 行く → 行った (itta)

The only godan verb that breaks its sound change rule.

3. Double-conjugating the negative

❌ 飲みませんでしなかった ✅ 飲みませんでした

The polite negative past is ません + でした. Don't mix polite and plain endings.

4. Using past tense for "I have been doing"

In English, "I have studied Japanese for two years" uses a kind of past/present mix. In Japanese, ongoing situations use the present tense:

❌ 二年間日本語を勉強しました。(implies you stopped) ✅ 二年間日本語を勉強しています。(you're still studying)

Use past tense only for completed actions.

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How to Practice

1. Narrate your yesterday: 昨日七時に起きました。朝ご飯を食べました。学校に行きました… Write the whole day in ます past tense.
2. Drill the sound changes: Take every godan verb you know and convert it to plain past. Focus on the groups that trip you up.
3. Convert between polite and plain: Take your "yesterday" paragraph and rewrite it in plain form. 起きました → 起きた. 食べました → 食べた.
4. Practice negative past: What didn't you do yesterday? 運動しませんでした。映画を見ませんでした。

The past tense unlocks storytelling. You can now talk about what happened, what you did, and what you experienced. That's a huge part of real conversation.

過去形をマスターしましょう！ (Kakokei o masutā shimashō!) — Let's master the past tense!