Simple form of Japanese verbs: present, past, and negative

THE simple form of Japanese verbs is not a single conjugation. It brings together four combinations: affirmative and negative in the non-past, as well as affirmative and negative in the past. The dictionary form is just the affirmative version of the non-past, such as 書く (to write) and 食べる (to eat).

These forms appear at the end of casual speech, but also within grammatical constructions used in polite sentences. Therefore, “simple form” is a more accurate name than treating them all just as “informal mode.”.

The four simple forms in a table

O Marugoto's chart of polite and simple forms, from the Japan Foundation, organizes exactly these four combinations. It also records important special forms, such as ある → ない and 行く → 行った.

Dictionary form is not infinitive

The dictionary form gets its name because it is the entry used to look up a verb. It is not a “primitive” form nor does it correspond perfectly to the Portuguese infinitive. In Japanese, this same form already functions as a predicate and expresses an event in the non-past.

The non-past can indicate habit, general truth, current state, or future, depending on the verb and context:

• 毎日、日本語を勉強する。
  まいにち、にほんごをべんきょうする。
  Mainichi, Nihongo o benkyō suru.
  I study Japanese every day.
• Tomorrow, I will meet a friend.
  Ashita, tomodachi ni au.
  Ashita, tomodachi ni au.
  I will meet a friend tomorrow.

Thus, calling 書く it just “present” erases an important difference. Japanese opposes past and non-past; expressions like every day and 明日 help define the temporal reading.

First, identify the verb group

The transformation depends on the group. If this classification still causes doubt, review the godan, ichidan, and irregular verbs before applying the rules below.

• Group 1, or godan: the last mora changes, as in 書く, 読む, and 帰る.
• Group 2, or ichidan: the final る is removed before various endings, as in 見る and 食べる.
• Group 3: brings together the patterns of する and 来る.

Not every verb ending in -iru or -eru belongs to Group 2. 帰る, 走る, 切る and 要る, for example, are Group 1.

How to form the non-past negative

Group 1: change the last mora to the a-line

In godan verbs, the final mora changes to the corresponding one with an a sound a and receives ない. The ending う is the special case: it changes to わ, not あ.

ある is special: its simple negative is ない, and not あらない.

Groups 2 and 3

In Group 2, remove る and add ない: 見る → 見ない and 食べる → 食べない. In Group 3, memorize the two central patterns: する → しない and 来る → 来ない（こない）.

How to form the affirmative past

The simple past of Group 1 follows the same sound groupings as the て form. The Marugoto's verb conjugation appendix allows you to compare dictionary, て, た, and ない forms side by side.

The most frequent exception is 行く → 行った. In Group 2, remove る and add た: 見る → 見た and 食べる → 食べた. In Group 3, use する → した and 来る → 来た（きた）.

How to form the negative past

After producing the form in ない, remove the い final and add かった. The procedure applies to the three groups:

• 書かない → 書かなかった (did not write);
• 食べない → 食べなかった (did not eat);
• しない → しなかった (did not do);
• 来ない → 来なかった（こなかった, did not come）;
• ない → なかった (there was not; there did not exist, for ある).

This regularity is useful: instead of memorizing another whole table, you start from the negative non-past form you already know.

When to use the plain form

At the end of the main clause, the plain style is common in casual conversations. The choice depends on the relationship between people and the situation, not just a fixed list of “friends and family.” The Irodori material on polite and plain styles emphasizes precisely this appropriateness to the interlocutor and context.

In a conversation between close people:

A: 明日、図書館に行く？
あした、としょかんにいく？
Ashita, toshokan ni iku?
Are you going to the library tomorrow?

B: うん、行く。
Un, iku.
Yeah, I'll go.

But the simple form also appears inside polite sentences, before elements that require that connection:

日本へ行くと思います。
にほんへいくとおもいます。
Nihon e iku to omoimasu.
I think I'll go to Japan.

行く is in the simple form before と, while 思います keeps the polite ending. This shows why “simple form” and “informal speech” are not exactly the same thing.

Simple form before nouns and other structures

The four simple forms can directly modify a noun. The Marugoto notes on verb + noun show the full contrast between 食べる, 食べない, 食べた and 食べなかった.

朝ごはんを食べない人です。
あさごはんをたべないひとです。
Asa-gohan o tabenai hito desu.
He is a person who doesn't eat breakfast.

Other common constructions include:

• verb + こと: 日本語を勉強すること (studying Japanese);
• clause + と思います: 来ると思います (I think he'll come);
• clause + んです: ちょっと聞きたいんです (it's that I'd like to ask something);
• verb + noun: 昨日買った本 (the book I bought yesterday).

To build complete sentences with these elements, also check the guide on how to form sentences in japanese.

Common mistakes with the plain form

• Calling the dictionary form the infinitive: the comparison can help at first, but it doesn't describe all Japanese functions.
• Confusing the plain form with a single ending: it includes る, ない, た, and なかった, depending on tense and polarity.
• Always translating the non-past as present: 明日行く usually indicates future.
• Classifying every verb ending in -iru or -eru as Group 2: confirm exceptions like 帰る and 走る.
• Using the plain form at the end of any conversation: evaluate the relationship, situation, and expected level of politeness.
• Inserting spaces within the conjugation: write 買わない, not 買わ ない.

Commented exercise

Transform each verb into the four forms: non-past affirmative, non-past negative, past affirmative, and past negative.

1. 書く: 書く・書かない・書いた・書かなかった.
2. 食べる: 食べる・食べない・食べた・食べなかった.
3. 行く: 行く・行かない・行った・行かなかった. The past affirmative is special.
4. する: する・しない・した・しなかった.
5. 来る: 来る（くる）・来ない（こない）・来た（きた）・来なかった（こなかった）.

As a quick reference rule: identify the group, form the negative with ない, form the past with た, and derive the past negative by swapping the い of ない for かった.

Next Steps

After mastering the four simple forms, compare them with the masu form of verbs. Then, practice the て-form and the potential form. To review the place of these forms in the language system, return to the Basics of Japanese Grammar.