ぶんぽう (Grammar)

To talk about actions that happened in the past, change the polite verb endings as follows:

Non-Past		Past
…ます	→	…ました
…ません	→	…ませんでした

Notice that only the polite ending changes. The verb stem remains the same.

	Non-Past		Past
ロバートくんは２時に	ねます。	→	ねました。	Robert went to bed at 2.
ロバートくんは９時に	おきます。	→	おきました。	Robert woke up at 9.
ロバートくんはビデオを	見ます。	→	見ました	Robert watched TV.
田中さんは がっこうに	行きません。	→	行きませんでした。	Tanaka did not go to school.
田中さんは でんわで	話しはなしません。	→	話しはなしませんでした。	Tanaka didn't talk on the phone.

Unlike English, Japanese does not distinguish between the simple past (e.g., "watched") and the present perfect (e.g., "have watched"). The past form simply indicates that the action occurred before the present. The exact interpretation depends on the context.

The following are common interjections.

• ええと is mainly used when the speaker is searching for the right word, remembering information, or organizing their thoughts. It is directed more toward the speaker's own thinking process (e.g., ええと…朝ねぼうしました: Umm...I overslept.).
• あのう is often used when the speaker is about to ask a question, make a request, interrupt someone, or begin speaking politely. It helps get the listener's attention while softening what follows (e.g., あのう…はらじゅくえきはどこですか: Excuse me. Where is Harajuku Station?).
• あれ？　is a common interjection used to express mild surprise, confusion, or the sudden realization that something is unexpected or different from what you expected. Depending on the situation, it can be translated as "Huh?", "Oh?", "Wait...", or "That's strange..." (e.g., あれ？　スマホがない: Oh, my smartphone is gone!"). (Although it has the same pronunciation as the demonstrative pronoun あれ ("that one over there"), the interjection あれ？ does not refer to any person or object.)
• ねえ is an informal interjection used to get someone's attention before speaking. It is similar to あのう, but sounds more casual and is commonly used among friends and family members. Depending on the context and intonation, it can be translated as "Hey," "Say," or "You know..."
  
  

In Lesson 3, we learned that the particle から (“from”) can mark the starting point of physical movement (私はかんこくから来ました: I came from South Korea.). The particle まで ("to/as far as") marks the endpoint of physical movement.

• すずきさんは、とうきょうから おおさかまで 行きました。
  Ms. Suzuki went from Tokyo to Osaka.

The particles から (“from”) and まで (“to/till”) are also used to indicate a period of time or an activity.

• 水曜日の午後４時半から５時半までミーティングがあります。 (Lesson 6)
  We have a meeting from 4:30 p.m. to 5:30 p.m. on Wednesday.
• 午後３時半から午前９時まで ねました。 (Lesson 8)
  I slept from 3:30 a.m. till 9 a.m.

Polite past noun and な-adjective sentences are formed by changing the copula です as follows:

Non-Past		Past
…です	→	…でした
…じゃありません	→	…じゃありませんでした

Non-Past		Past
先生です	→	先生でした	He/She was a teacher.
しずかです	→	しずかでした	It was quiet.
先生じゃありません	→	先生じゃありません でした	He/She wasn't a teacher.
しずかじゃありません	→	しずかじゃありません でした	It was not quiet.

The negative past can also be formed by changing ない to なかった:

Non-Past		Past
先生じゃ ないです。	→	先生じゃ なかったです。	H/She was not a teacher.
しずかじゃないです。	→	しずかじゃありませんでした	It was not quiet.

For negative past forms, an alternate pattern can also be used. In this pattern, the non-past negative form ない changes to the past negative form なかった, as shown below.

		Negative	Polite
Non-Past	先生じゃ	ない	です。	He/She is not a teacher.
	しずかじゃ	ない	です。	It is not quiet.
		↓
Past	先生じゃ	なかった	です。	He/She was not a teacher.
	しずかじゃ	なかった	です。	It was not quiet.

Notice that the second pattern parallels the past-tense formation of い-adjectives, where …ない changes to …なかった.

The frequency expressions introduced earlier (いつも, たいてい, ときどき, あまり, ぜんぜん, etc.) describe approximate frequency (e.g., usually, sometimes, rarely). To state exactly how many times an action occurs within a given period, use the following pattern:

Time Frameに

Frequency

To state the exact number of times an action occurs, Japanese uses two frequency counters (かい or ど). Both means "times" (number of occurrences). The particle に is required after the time frame, while no particle is used after the frequency expression. The approximation suffix ぐらい (“about”) may be added after the frequency (e.g., ２かいぐらい).

Time Frameに	Frequency
一週間( いっしゅうかん)に	何回(なんかい)	かいものしますか。	How many times a week do you go shopping?
一週間に	２かい	かいものを します。	I go shopping twice a week.
一日(いちにち)いちに	３ど	ごはんをたべます。	I eat three times a day.

The following table shows the frequency counter かい for numbers 1–10. While ど is commonly used for once, twice, and three times, かい is the standard counter for four or more times. ✅ indicates exceptions in pronunciation.

１ど（いちど）	１かい（いっかい）✅	once
２ど （にど）	２かい （にかい）	twice
３ど （さんど）	３かい （さんかい）	three times
…	４かい （よんかい）	four times
	５かい （ごかい）	five times
	６かい （ろっかい）✅	six times
	７かい （ななかい)	seven times
	８かい （はちかい or はっかい）✅	eight times
	９かい （きゅうかい）	nine times
	１０かい （じゅっかい) ✅	ten times
なんど（ぐらい）	なんかい（ぐらい）	How many times?
どのぐらいよく		How often?

To state how long an activity lasts (its duration), use the following pattern:

Time Frameに

Duration

Action

The particle に follows the time frame, while no particle is used after the duration. The approximation suffix ぐらい ("about") may be added after the duration (e.g., ８時間ぐらい).

Time Frameに	Duration	Action
一日(いちにち)にいちにちに	どのぐらい	ねますか。	How long do you sleep a day?
一日(いちにち)にいちにちに	８時間	ねます。	I sleep eight hours a day.
一時間(いちじかん)に	１０分	やすみます。	I take a break for ten minutes an hour.
	何分(なんぷん)なんぷん(ぐらい)		How many minutes?
	何時間(なんじかん)(ぐらい)		How many hours?
	何日(なんにち)(ぐらい)		How many days?
	何週間(なんしゅうかん)(ぐらい)		How many weeks?
	何(なん)か月(げつ)(ぐらい)		How many months?
	何年(なんねん)(ぐらい)		How many years?

Particle で marks the means and tools to do something. Do not confuse this with the particle で (at) that makrs the location of activities.

(い)

	Meansで
ごはんはわ	はしで	食(た)べます。	We eat rice with chopsticks.
Breadはわ	日本ごで	パンといいます。	"Bread" is called "pan" in Japanese.
マイアミまで	ひこうきで	行(い)きました。	I flew to Miami.
そのニュースを	インターネットで	読(よ)みました。	I read the news on the Internet.
けんちゃんは	ビデオゲームで	あそびました。	Ken had fun with video games.
くうこうに	でんしゃで	行(い)きました。	I went to the airport by train.

Particle で also marks the cause, reason, or circumstance that results in the following state. It can often be translated as "because of," "due to," or "with."

( い )

	Cause/Reasonで
私は	クラスプロジェクトで	いそがしいです。	I'm busy with the class project.
ＧＴは	ロボットけんきゅうで	ゆうめいです。	GT is famous for its robotics research.

Japanese speakers often begin a conversation by giving a brief introductory remark before asking a question or making a request. In this use, the particle が (or its more casual counterpart けど) marks the opening statement and signals that more is coming. Rather than expressing a strong contrast ("but"), these particles function as a conversation opener, softening what follows and making it sound less abrupt.

1. ちょっと 聞(き) きますが、はらじゅくえきはわどこですか。
   Excuse me (Lit. Let me ask you something), but where is Harajuku Station?
2. あのう、すみませんけど、今(いま)、何時(なんじ)ですか。
   Excuse me, but what time is it?

This pattern is common not only when starting a new conversation with someone, but also when making a slight shift of topic during an ongoing conversation: "I'd like to ask or mention something else now," without making the transition sound too sudden.

3. ちょっとしつもんですけど、そのビデオはありますか。
   I have a question, but do you have the video?

The same pattern is also used to introduce a context or premise that the following sentence should be understood in light of.

4. あした、しけんがありますが、べんきょうしましたか。
   We'll have an exam tomorrow. (In light of this) did you study?
5. Emailを書(か)きましたけど、読(よ)みましたか。
   I wrote you email. (In light of this) did you read it?
6. 私はここの学生ですが、それはいくらですか。
   I am a student here. (In light of this) how much is it?

In Japan, many stores, transportation services, and other facilities offer student discounts. By saying 私はここの学生ですが… (I'm a student here, but...), the speaker is implicitly asking whether a student discount applies. The listener naturally understands the intended meaning: I'm a student here. Is there a student price? If so, how much is it? Japanese often leaves this type of information implicit, relying on the listener to infer the speaker's intention from the context.

The past tense of affirmative い-adjectives can be formed by changing the ～い ending to ～かった as shown below. ✅ The past form of いいです is an exception: いいです → よかったです, not いかったです.

Non-Past		Past
おもしろい です	→	おもしろかった です	It was interesting.
たかい です	→	たかかった です	It was expensive.
いい です	→	よかった です✅	It was good.

The past tense of negative い-adjecitves (～くないです and ～くありません) can be formed by applying the same past-tense formation rule of な-adjectives (～じゃないです and ～じゃありません): ないです → なかったです and ありません → ありませんでした as shown below:

Non-Past		Past
おもしろく ない です おもしろく ありません	→	おもしろく なかった です おもしろく ありません でした	It was not interesting.
たかく ないです たかく ありません	→	たかく なかったです たかく ありません でした	It was not expensive.
よく ないです よく ありません	→	よく なかったです よく ありません でした	It was not good.

The following shows how い-adjective question-answer is used in a conversation:

A:	かいましたか。	Did you buy it?
B:	ええ、かいました。	Yes, I did.
A:	たかかった ですか。	Was it expensive?
B:	いいえ、たかく ありません でした。 (or たかく なかったです。)	No, it wasn't.
A:	よかった ですね。	That's great!

⚠	The です to でした conjugation to create a past-tense form works ONLY for noun and な-adjective sentences. This conjugation is ungrammatical for い-adjective sentences.

Noun	かようびでした	It was Tuesday.
な-Adj.	きれいでした	It was pretty.
い-Adj.	✽ おもしろいでした	[Ungrammatical]

The correct past form of おもしろいです is おもしろかったです.

1.

う-Verbs

The plain, non-past negative う-verbs can be formed by using the similar verb stem-based plain う-verb formation rule we used in Lesson 7. (✅ indicates an exception below.)

If stem ends with	change it to...	add ない	Examples
…き	か	ない	かきません → かかない	not write
…ぎ	が	ない	およぎません → およがない	not swim
…し	さ	ない	はなしません → はなさない	not speak
…り	ら	ない	つくりません → つくらない ありません → ない✅	not make there is not
…い	わ	ない	かいません → かわない	not buy
…ち	た	ない	まちません → またない	not wait
…み	ま	ない	のみません → のまない	not drink
…び	ば	ない	よびません → よばない	not call
…に	な	ない	しにません → しなない	not die

２.

る-Verbs

The plain negative form of る-verbs is formed by simply changing ません to ない.

Polite	Plain
おきません	→ おきない	not wake up
みません	→ みない	not watch
たべません	→ たべない	not eat
いません	→ いない	not be/not stay
ねません	→ ねない	not go to bed/not lie down

3. Irregular Verbs

The plain negative forms of the irregular verbs are formed by changing ません to ない.

Polite	Plain
しません	→ しない	not do
きません	→ こない	not come

You might think that adding です to a plain negative verb, such as 行かない, makes it polite. However, this does not work with verbs. Verbs express politeness through their own endings, so 行かない is already the complete plain negative form. Adding です does not make it more polite—it simply makes the sentence ungrammatical.

• ✗ 行かないです (nonstandard in traditional grammar)
• ✓ 行きません (polite)
• ✓ 行かない (plain)

✅ Note: In casual conversation, you may hear forms such as 行かないです. Although common in modern spoken Japanese, this textbook uses the standard polite form 行きません.

To change polite adejctive and noun sentences into plain sentences, use the following rules.

• い-Adjectives
  • Affirmative: Delete です.
  • Negative: Delete です, or change ありません to ない.
• な-Adjectives and Nouns:
  • Affirmative: Change です to だ.
  • Negative: Delete です, or change ありません to ない.

	Polite Forms	Rules		Plain Forms
い-Adj.	たかいです。 たかくないです。 たかくありません。	Delete です. Delete です. Change ありません to ない.	→	たかい。 たかくない。 たかくない。
な-Adj. & Noun	きれいです。 先生です。 きれいじゃないです。 先生じゃないです。 きれいじゃありません。 先生じゃありません。	Change です to だ. Change です to だ. Delete です. Delete です. Change ありません to ない. Change ありません to ない.	→	きれいだ。＝ きれい。✅ 先生だ。＝ 先生。✅ きれいじゃない。 先生じゃない。 きれいじゃない。 先生じゃない。

✅ だ is often omitted in an informal conversation to avoid sounding too blunt. See below.

Now that you know how to form the plain forms, let's look at the social and pragmatic contexts in which they are used. Plain-form sentences are commonly used in informal conversations among family members, close friends, and other people with whom the speaker has a comfortable, informal relationship.

Plain-Form Questions Informal Interjections Omitting だ

Compare this conversation in the polite style with the same conversation in the informal style.

A and B are acquaintances.	A and B are close friends.
A: きょう、がっこうに 行きますか。 B: いいえ、行きません。 A: ああ、そうですか。 じゃ、今、いそがしくないですね？ B: ええ。ひまですよ。	A: きょう、がっこうに 行く？ B: ううん、行かない。 A: ああ、そう。 じゃ、今、いそがしくないね？ B: うん。ひまよ。 [feminine] うん。ひまだよ。

🌸	Cultural Notes

1. The polite form is the default choice in Japanese, especially when speaking with someone you do not know well, someone older, or someone in a higher social position, such as a teacher, supervisor, or customer. Using the polite form shows respect and consideration for the listener and helps create a positive first impression.
2. The plain form is commonly used with family members, close friends, and others with whom you have developed an informal relationship. Because it sounds more direct and personal, using it with strangers or people of higher status may come across as overly familiar or impolite.
3. One important difference from English is that becoming friends does not automatically mean switching to the plain form. Some Japanese people continue using polite speech with friends, coworkers, neighbors, or even family members out of habit or personal preference. The choice depends not only on closeness but also on age, personality, workplace culture, and the situation.
4. When in doubt, begin with the polite form. As your relationship develops, you may naturally shift to the plain form if the other person does the same or if the situation becomes more informal. In Japanese, it is generally better to sound too polite than not polite enough.

The connective から is used to state a reason or cause. It follows the pattern: /S1 から、S2/.　S1 is the reason or cause. S2 is the result, decision, or conclusion based on that reason. In other words, S1 explains why S2 is true.

Reason or Cause + から (S1)	Result or Conclusion (S2)
やさいがきらいだ (or きらいです) から、	やさいは食べません。
Because I dislike vegetable,	I don't eat vegetable.
きょうは 日曜日だ (or 日曜日です) から、	じゅぎょうは ありません。
Because it's Sunday today,	I don't have a class.
おいしかった (or おいしかったです) から、	たくさん 食べました。
Because it was delicious,	I ate a lot.
あした 行かない (or 行きません) から、	きょう 行きます。
Because I'm not going tomorrow,	I'm going today.

Because から connects two clauses, you must pay attention to the politeness level of both S1 and S2. When S1 is in the plain form and S2 is in the polite form, the entire sentence is interpreted as polite. This pattern is very common and completely natural in spoken and written Japanese.

• やさいがきらいだから、あまり食べません。
• おいしいから、たくさん食べます。
• あした行くから、今日は行きません。

Reversing this pattern—using the polite form in S1 and the plain form in S2—sounds awkward and unnatural in Japanese. Because S2 is the speaker’s main assertion, and ending the sentence in the plain form lowers the politeness level abruptly, contradicting the polite setup introduced in S1.

• やさいがきらいですから、あまり食べない。[Unnatural]
• おいしいですから、たくさん食べる。[Unnatural]
• あした行きますから、今日は行かない。[Unnatural]

⚠	Common Pitfall for English Speakers

English speakers often assume that から works exactly like the English word “because.” Be careful—they organize information in opposite directions. In Japanese, the pattern is always:

Cause / Reason → から → Result / Conclusion

In English, however, the word because often comes after the result. Suppose you want to say:

I won’t go there because that restaurant is expensive.

An English speaker might incorrectly arrange the Japanese sentence as follows:

私は行きませんから、 あのレストランはたかいです。
Because I won’t go there, that restaurant is expensive.

Clearly, the cause and result have been reversed, and the logic no longer makes sense. To express the intended meaning, the reason must come first:

あのレストランはたかいですから、私は行きません。

Because that restaurant is expensive, I won’t go there.

Japanese has two distinct speaking modes. One is the report mode, which presents information as a neutral statement of fact. This is the mode you have practiced so far. The other is the explanation mode, which is used to provide background information, justification, or a reason for what follows. Dialogue 1 introduces this explanation mode, which is typically marked by sentence endings such as ～んです (the conversational form of the more formal ～のです).

Consider the following situation. You are waiting for a bus, but it is running late, and you are worried that you will miss an appointment. If you state this fact by itself, without reference to the listener or the surrounding context, you can use the report mode:

1. バスが きません。The bus isn't coming.

Sentence 1 is grammatically correct, but it simply reports a fact. It does not convey the explanatory or apologetic tone that would be natural when you are explaining why you will be late. To sound as though you are giving a reason for being late—implicitly offering an explanation—you switch to the explanation mode:

2. バスが こないんです。　　It's that the bus is not coming.

By using ～んです as in Sentence 2, the speaker presents the information as an explanation of why something is the case, rather than as a simple factual statement.

The predicate that comes before んです must be in the plain form. This is because んです functions as a fixed explanatory ending rather than a regular predicate. As a result, んです itself does not conjugate: it never changes to a past form (んでした) or a negative form (んじゃないです) as shown in Sentences 3 to 6 below.

3. かえるんです。　　It's that (someone) is going home.
4. かえらないんです。　　It's that (someone) is not going home.
5. たかいんです。　　It's that it is expensive.
6. たかくないんです。　　It's that it is not expensive.

If the plain, non-past copula だ is combined with んです, だ changes to な as shown below.

Plain Form + んです
日曜日だ + んです	→	日曜日なんです	It's that it's Sunday.
ひまだ + んです	→	ひまなんです	It's that I'm free.

どうして (Why?) questions are typically combined with んですか ending. To answer a why-question, use either ～からです or ～んです as shown below.

A:	どうして	わさびを たべない	んですか。	Why don't you eat wasabi?
B:		わさびは きらいだ	からです。	It's because I dislike wasabi.
		わさびは きらいな	んです。	It's that I dislike wasabi.

⚠	Do not combine からです and んです into one form (i.e., ～んからです is ungrammatical).

Even though んです is a fixed expression that does not conjugate, the politeness level of the explanatory ending can vary. While ～んです is polite, the same explanatory meaning can be expressed at different levels of formality, as shown below:

A and B are acquaintances.	A and B are friends.
A: どうしてビールを飲まないんですか。 B: あした、テストがあるんです。 A: ああ、そうなんですか。	A: どうしてビールを飲まないの？ B: あした、テストがあるんだ。 or あした、テストがあるの。[feminine] A: ああ、そうなんだ。

Finally, the question form ～んですか should be used with care. For example, when you say いいんですか, you are not simply asking whether something is good, correct, or acceptable. You are also implying that the situation calls for an explanation—and in some contexts, this implication may sound like a request for justification or even an apology.