The Irregular Verbs する & 来る
Of all the verbs in Modern Japanese, only two are considered irregular. These verbs are する meaning “to do” and 来る meaning “to come.” Their irregularity lies in their unique set of bases. First, we will learn what those bases are, then study how they combine with the endings we know.
In our terminology rap, only terms related to the bases are listed. If a grammar term appears that you are still unsure about, refer to past lessons.
- Base: One of the six forms of a verb that is followed by endings like auxiliaries.
- Terminal/Predicative Form (終止形): Marks the end of a complete sentence/the predicate.
- Attributive Form (連体形): Makes a verb, adjective, etc. into a modifier that goes directly before a noun.
- Basic Form (基本形): The basic or “plain speech” form of any given phrase. The basic form encompasses both the predicative and the attributive forms in the context of verbs and adjectives.
- Continuative Form (連用形): Used with endings pertaining to actions being carried out.
- Irrealis Form (未然形): Used with endings which indicate actions that have yet to occur.
The Bases of する (To Do)
So far, we know about the terminal/predicative form (終止形), the attributive form (連体形), the continuative form (連用形), and the irrealis form (未然形). Although its verb class is only composed of itself, する combines with many words to create more verbs, especially word roots of Sino-Japanese and foreign origin, and with its basic meaning of “to do,” it is arguably the most important verb in Japanese.
Terminology Note: する itself, along with all the verbs it creates, are collectively known as サ行変格活用動詞 (“sa”-column irregular conjugating verbs) or Sahen サ変 verbs for short.
| Class | Example | Predicative | AttributivE | Continuative | Irrealis |
| Ichidan | 見る (to see) | Miru | Miru | Mi– | Mi– |
| Godan | 聞く (to ask) | Kiku | Kiku | Kiki– | Kika– |
| Sahen | する (to do) | Su(ru) | Suru | Shi– | Shi– |
※The root of する is s-. What follows this root are the affixes which create the bases themselves. Applying this logic by comparing it to other verb classes reveals just how irregular it truly is.
※The traditional predicative/terminal form is す. Its use in everyday speech is few and far between, but it is fairly common in set phrases, poetry, etc.
※One thing that Ichidan and Sahen verbs share is how the affix ～る marks the attributive form. This does not transfer over to Godan verbs, including those which end in /ru/ because the /r/ is a part of the stem for those verbs.
The Conjugations of する
Now it is time to see how する conjugates for the forms we have learned thus far. Below, you will see how its irrealis form (for the negative auxiliary ～ない) and its continuative form (for most auxiliaries like ～ます for politeness and ～た for past tense) are both し～.
As only the bases of する are different, we will forego an etymological breakdown of these conjugations (see Lesson 17 or Lesson 18). However, the base of する used for each conjugation will still be listed.
| Form | Conjugation | Base of する |
| Non-Past (Plain) | する | Terminal/Attribute Form |
| Non-Past (Polite) | します | Continuative Form |
| Past (Plain) | した | Continuative Form |
| Past (Polite) | しました | Continuative Form |
| Negative (Plain) | しない | Irrealis Form |
| Negative (Polite Method 1) | しません | Continuative Form |
| Negative (Polite Method 2) | しないです | Irrealis Form |
| Negative Past (Plain) | しなかった | Irrealis Form |
| Negative Past (Polite Method 1) | しませんでした | Continuative Form |
| Negative Past (Polite Method 2) | しなかったです | Irrealis Form |
When the auxiliary verb ～ます is conjugated into its negative form ～ません, it utilizes its own irrealis form mase- to do so, and this does not change how ～ます attaches to the continuative form of the main verb する.
Speech Level Note: As we learned with Ichidan and Godan verbs, regarding the negative and negative past in polite speech, Method 1 is politer and more appropriate than Method 2 in formal settings.
1. 僕は宿題をしなかった。
I didn’t do my homework.
2. 変なことをする。
To do something weird.
3. いい仕事をしますね。
You do a good job, don’t you.
4. 弟は掃除をしました。
My little brother did cleaning.
5. 嫌なことはしないです。
I won’t do anything unpleasant.
6. 皿洗いはしません。
I won’t do the dishes.
7. 料理をしませんでした。
I didn’t cook.
8. 小さい頃は勉強をしなかったです。
I didn’t study when I was young/small.
The Meanings of する
する is not only irregular, but it also has several meanings, all of which are very important to harness even as a beginner.
“To DO” on a Grander Scale
Firstly, する is “to do” in a much larger sense both grammatically and semantically speaking than its English counterpart. In Japanese, words usually cannot be used as another part of speech without a change in word form. For example, the noun for “yawn” is あくび, but “to yawn” is あくびをする. Even if “to do” is not used in this way in English, する helps many nouns behave as verbs. You can alternatively think of it as “to perform the act of…”
11. 息をする。
To breathe.
12. 恋をする。
To be in love.
13. 旅をする。
To go on a journey.
14. 火傷をする。
To burn (oneself).
15. 仕事をする。
To work (a job).
Noun + する
Most importantly, する helps make many words, mostly Sino-Japanese and loanwords, function as verbs. For instance, 運転 means “driving,” but to say “to drive,” you say 運転（を）する. When to include を will be a discussion for another time, but for now, if its inclusion is not necessary, it will be left in parentheses.
| 注文する | To order | 翻訳する | To translate |
| サインインする | To sign-in | キャンセルする | To cancel |
| 電話する | To call on the phone | 勉強（を）する | To study |
| 販売する | To sell/market | 投票する | To vote |
16. 今夜電話しますね。
I’ll call you tonight, ok?
17. 英文を翻訳しました。
I translated the English sentences.
18. Tシャツを販売します。
(I/we) will sell T-shirts.
19. カレンダーを注文しませんか。
How about ordering a calendar?
20. 今回は投票しませんでした。
I did not vote this time.
21. フィンランド語の勉強をしました。
I did my Finnish studies.
22a. 広東語を勉強しませんか。〇
22b. 広東語を勉強をしませんか。X
Why don’t you study Cantonese?
23. 勉強(を)しませんか。
Why don’t you/we study?
Grammar Note: In Ex. 21, 勉強 is attached to the previous noun with の to create the sense of “studies.” However, simply saying “I study…” involves using 勉強 as a verb with する. Grammatically, を cannot be used twice in the same clause like in 22b. If the object were dropped like in Ex. 23, を is optional with its inclusion most likely used in settings like in Ex. 21.
To Cost
There are several ways to say “to cost” in Japanese, but we will only focus on how する is used in this way. In this meaning, it functions as an intransitive verb with the value phrase functioning as an adverb. The “cost” is the sticker price which the speaker pays for it.
24. レンタルもおおよそ五千円します。
Rental also costs about 5000 yen.
25. LINEスタンプは百円します。
LINE stamps cost 100 yen.
26. このワインは二千円もしませんでした。
This wine didn’t even cost 2000 yen.
To Wear an Accessory
There are many verbs in Japanese meaning “to wear,” but する can specifically express wearing an accessory.
27. マスクをする。
To wear a mask.
28. 手袋をする。
To wear gloves.
29. ネクタイをする。
To wear a tie.
To Sense
する can also be used to mean “to sense” as in the five senses as well as emotions. These are treated as natural phenomena beyond the control of the speaker; thus, this usage is intransitive in nature even though the corresponding English phrases will most likely be transitive. This means that が will mark what would correspond to the object in English.
30. 強い匂いがしました。
There was/it had a strong scent.
31. 甘い味がしますね。
It tastes sweet, doesn’t it?
32. 量が少ない感じがしました。
I felt that the amount was lacking.
33. 変な音がした。
There was a strange sound.
34. 悲しい気持ちがする。
To have sad feelings.
To Be…. (Occupation/Role)
When you want to say your job/role/occupation is, you typically use する. However, to make this an active statement, you need to use the ending ～ている, which indicates an ongoing state.
35. 料理人をしています。
I am a cook.
36. 銀行員をしています。
I am a bank clerk.
To Be/Have
する may translate as “to be/have” as in “to take on” a certain quality. Key phrases of this include the following:
| ～形をする | To take the form/shape of… | ～顔をする | To have a…face |
| ～目付きをする | To have a…expression | ～目をする | To have… eyes |
37. ｛丸い・四角い｝形をした建物を構築する。
To construct a [round/square] shaped building.
38. あの子はかわいい顔をしていますね。
That kid has a cute face, doesn’t he/she?
39. 鋭い目付きをする。
To have a sharp expression.
40. 冷たい目をする。
To have cold eyes.
To Play
The act of playing some specific game or sport is expressed with する. In fact, する also encompasses doing general activities of any sort.
Word Note: In casual contexts, you may also use the verb やる for this meaning.
41. パチンコをしませんか。
Why not play pachinko (Japanese pinball)?
42. 生け花をします。
I will practice flower arrangement.
43. アメフトを｛します・やります｝。
I’ll play American football.
44. スキーはしません。
I don’t ski.
45. 私は昨日、サッカーをしました。
I played soccer yesterday.
The Bases of 来る (To Come)
来る meaning “to come” has its own unique set of bases, which is the sole reason for why it is viewed as an “irregular” verb.
Terminology Note: The verb class which 来る belongs to is called 行変格活用動詞 (“ka”-column irregular conjugating verbs) or Kahen カ変 verb for short.
| Class | Example | Predicative | Attributive | Continuative | Irrealis |
| Ichidan | 食べる (to eat) | Taberu | Taberu | Tabe– | Tabe– |
| Godan | 死ぬ (to die) | Shinu | Shinu | Shini– | Shina– |
| Sahen | する (to do) | Suru | Suru | Shi– | Shi– |
| Kahen | 来る (to come) | Kuru | Kuru | Ki– | Ko– |
※Similarly to suru する, the stem of kuru 来る is k-. Also just like suru する, its terminal/predicative form was originally just ku 来, but this is no longer used.
The Conjugations of Kuru 来る
Now it is time to see how 来る conjugates for the forms we have learned thus far. Below, you will see how its irrealis form ko– (for the negative auxiliary ～ない) and its continuative form ki- (for most auxiliaries like ～ます for politeness and ～た for past tense) are NOT the same.
As only the bases of 来る are different, we will forego an etymological breakdown of these conjugations (see Lesson 17 or Lesson 18). However, the base of 来る used for each conjugation will still be listed.
| FORM | CONJUGATION | BASE OF する |
| Non-Past (Plain) | くる | Terminal/Attribute Form |
| Non-Past (Polite) | きます | Continuative Form |
| Past (Plain) | きた | Continuative Form |
| Past (Polite) | きました | Continuative Form |
| Negative (Plain) | こない | Irrealis Form |
| Negative (Polite Method 1) | きません | Continuative Form |
| Negative (Polite Method 2) | こないです | Irrealis Form |
| Negative Past (Plain) | こなかった | Irrealis Form |
| Negative Past (Polite Method 1) | きませんでした | Continuative Form |
| Negative Past (Polite Method 2) | こなかったです | Irrealis Form |
When the auxiliary verb ～ます is conjugated into its negative form ～ません, it utilizes its own irrealis form mase- to do so, and this does not change how ～ます attaches to the continuative form of the main verb 来る.
The Meaning of 来る
来る means “to come” in both spatial and temporal contexts. The difference it has with its English equivalent is that it means “to come” as in someone/something arriving at Point A (from Point B). In a directional sense, it never describes moving away from where the speaker is at the time of utterance.
46. サンタさんが来なかった。
Santa didn’t come.
47. ついに春が来た！
Spring has finally arrived/come!
48. 電車、来ないよ。
The train hasn’t come!
49. 来る日も来る日も雪だった。
It was snow day after day.
50. 連絡が来ませんでした。
No contact has come in.
51. 手紙が｛来なかった・届かなかった｝です。
A letter didn’t come.
Synonym Note: In the sense of “to arrive” as in something that is delivered, the verb 届く is preferred but not required.
52. 明日のパーティに来る？
Will you come to [my/the] party tomorrow?
Grammar Note: Even though the speaker of this sentence is not necessarily at Point A (where the party is being held), their state of mind is, and when this is the case, using 来る is still valid.