N3Chapter 50Unit 3 · Purpose, Cause, and Evidence

Expressing Reasons

Learning objectives

  • Choose から, ので, or ため according to tone and the type of explanation.
  • Use おかげで for a positive result and せいで for blame or a negative result.
  • Connect nouns, adjectives, and verbs correctly before reason expressions.
  • Explain a decision or problem naturally in daily, school, and workplace contexts.
N3 context

At N4, you learned that から and ので can both mean “because.” At N3, the important question is not only why, but also how directly, politely, formally, positively, or critically you explain the reason. These choices shape the relationship with your listener.

Vocabulary語彙
5 terms

  • 延期

    noun

    えんき

    enki

    postponement

  • 間に合う

    verb

    まにあう

    maniau

    to be in time

  • 渋滞

    noun

    じゅうたい

    juutai

    traffic congestion

  • 助け

    noun

    たすけ

    tasuke

    help; assistance

  • 迷惑

    noun

    めいわく

    meiwaku

    trouble; inconvenience

1. A reason has a tone

Compare助詞

Choosing a reason expression

〜からdirect, personal explanation

今日は疲れたから、早く寝る。

Natural in conversation; can sound firm when giving a reason for your own decision.

〜のでsofter, more considerate explanation

少し遅れますので、先に始めてください。

Often preferred when speaking politely or making a request.

〜ためformal cause or official explanation

大雨のため、イベントは延期です。

Common in notices, announcements, and written Japanese.

〜おかげで / 〜せいでpositive help / negative blame

先生のおかげで合格できた。

Choose according to whether the result is welcome or unwanted.
Grammar文法
Plain form + から / ので

means Because; since.

Formation

Verb and い-adjective: plain form + から/ので. Noun and な-adjective: だ + から, but な + ので (静かなので, 学生なので).

Examples

明日は試験があるから、今夜は出かけない。

ashita wa shiken ga aru kara, konya wa dekakenai.

Because I have an exam tomorrow, I will not go out tonight.

この道は危ないので、気をつけてください。

kono michi wa abunai node, ki o tsukete kudasai.

Because this road is dangerous, please be careful.

駅に近いので、この店で待ちましょう。

eki ni chikai node, kono mise de machimashou.

Since it is close to the station, let us wait at this shop.
Grammar文法
N のため / plain form + ため

means Because of; due to. Formal and objective.

Formation

Noun + のため; verb plain form + ため; い-adjective + ため; な-adjective + なため.

Examples

事故のため、電車が遅れています。

jiko no tame, densha ga okurete imasu.

Trains are delayed due to an accident.

体調が悪いため、本日は休みます。

taichou ga warui tame, honjitsu wa yasumimasu.

I will be absent today because I am unwell.

不便なため、この方法は使われなくなった。

fuben na tame, kono houhou wa tsukawarenaku natta.

Because it was inconvenient, this method stopped being used.

2. Credit, blame, and responsibility

Grammar文法
N のおかげで / N のせいで

means Thanks to N (positive result) / because of N (negative result or blame).

Formation

Noun + のおかげで / のせいで. A clause can also come before おかげで or せいで.

Examples

友達が手伝ってくれたおかげで、レポートが間に合った。

tomodachi ga tetsudatte kureta okage de, repooto ga maniatta.

Thanks to my friend's help, I finished the report in time.

渋滞のせいで、会議に遅れてしまった。

juutai no sei de, kaigi ni okurete shimatta.

Because of the traffic, I ended up late for the meeting.

彼のせいで失敗した、と決めつけないほうがいい。

kare no sei de shippai shita, to kimetsukenai hou ga ii.

It is better not to jump to the conclusion that you failed because of him.

Do not use せいで for your own neutral explanation

電車が遅れたせいで、遅れました is possible, but it carries blame. For a neutral apology, use 電車が遅れたので、遅れました. Reserve せいで for a clearly unwelcome result.

雨なので、試合は中止になると思います。

ame na node, shiai wa chuushi ni naru to omoimasu.

Because it is raining, I think the game will be cancelled.

Noun + なので is polite and explanatory; 雨だから is more direct.

3. Context dialogue: changing a reservation

Calling a restaurant after a train delay会話
Mina

もしもし、七時に二人で予約しているミナです。

moshi moshi, shichi-ji ni futari de yoyaku shite iru Mina desu.

Hello, this is Mina; I have a reservation for two at seven.

Mina

事故のため電車が遅れているので、十分ほど遅れそうです。

jiko no tame densha ga okurete iru node, juppun hodo okuresou desu.

Because trains are delayed due to an accident, it looks like we will be about ten minutes late.

Clerk

承知しました。お席はそのままにしておきます。

shouchi shimashita. oseki wa sono mama ni shite okimasu.

Certainly. We will keep your table for you.

Mina

助かります。ご迷惑をおかけして、申し訳ありません。

tasukarimasu. gomeiwaku o okake shite, moushiwake arimasen.

That is a great help. I am sorry for the inconvenience.

Clerk

大丈夫です。お気をつけてお越しください。

daijoubu desu. oki o tsukete okoshi kudasai.

No problem. Please come safely.

4. Guided practice

Choose the best expression, then explain the tone.

  1. You tell a friend: “I am going home because I am tired.”
  2. You politely ask a teacher to begin without you because you will be late.
  3. A station notice: “Service is suspended due to strong winds.”
  4. You thank a classmate: “Thanks to you, I understood the assignment.”
  5. You complain that a noisy neighbour caused your poor sleep.
Check your answers
  1. 疲れたから、帰るね。 Direct, personal reason.
  2. 少し遅れますので、先に始めてください。 Softer and considerate.
  3. 強風のため、運転を見合わせています。 Formal public-notice style.
  4. あなたのおかげで、課題が分かりました。 Positive credit.
  5. 隣の部屋がうるさかったせいで、よく眠れなかった。 An unwanted result with blame.

5. Reading practice: a school announcement

本日の校外授業は、強風のため中止になりました。代わりに、三時から教室で映画を見ます。急な変更なので、全員に連絡できない可能性があります。友達が来ていない場合は、この知らせを伝えてください。先生方の準備のおかげで、授業の内容は来週も続けられます。

Reading check: Find (1) the formal cause, (2) the reason the school may not reach everyone, and (3) the positive result credited to the teachers.

Translation: “Today’s outdoor lesson has been cancelled because of strong winds. Instead, we will watch a film in the classroom from three o’clock. Because this is a sudden change, it may not be possible to contact everyone. If a friend has not come, please pass on this notice. Thanks to the teachers’ preparation, we can continue the lesson content next week.”

6. Communication and flashcard review

Speak or write: explain one changed plan using 〜ので, one formal notice using 〜ため, and one positive result using 〜おかげで.

Review flashcards: 〜から → direct personal reason; 〜ので → softer explanation; 〜ため → formal objective cause; 〜おかげで → positive result; 〜せいで → negative result/blame.

Guided practice練習

Choose the expression whose tone fits the setting.

  1. 1.Politely ask a teacher to start without you because you will be late.

  2. 2.Write a formal notice that service is suspended because of strong winds.

  3. 3.Thank a classmate because their help let you meet the deadline.
Reading practice読解

Outdoor lesson change

school announcement

Target: 3 minutes
本日の校外授業は、強風のため中止になりました。代わりに、三時から教室で映画を見ます。急な変更なので、全員に連絡できない可能性があります。友達が来ていない場合は、この知らせを伝えてください。先生方が早く準備してくださったおかげで、来週の授業予定を変えずに済みます。
校外授業（こうがいじゅぎょう）
lesson outside school
変えずに済む（かえずにすむ）
to manage without changing
  1. What is the formal cause of the cancellation?
  2. Why might the school not contact everyone?
  3. What positive result is credited to the teachers?
Listening rehearsal聴解

A delayed arrival

Listen for the neutral reason and the speaker's response.

Listen before opening the transcript.
  1. Why will the speaker be late, and what do they request?
Key takeawaysまとめ
  • 1から is direct and personal; ので softens an explanation or request.
  • 2ため is formal and objective, so it fits notices and written explanations.
  • 3おかげで gives positive credit; せいで marks an unwanted result or blame.
  • 4Nouns and な-adjectives use different connections: 学生だから but 学生なので; 静かなため.

Knowledge Check

Practice quiz
1 / 10

Which is best in a public transport announcement?