When learning Japanese, you may have come across the phrase 〜てしまう or its casual form 〜ちゃう. These expressions are commonly used in everyday conversation, but their meaning can be tricky for learners. In this blog post, we’ll break down the meaning and usage of 〜てしまう and 〜ちゃう with plenty of examples!

What Does 〜てしまう Mean?

The verb しまう in Japanese originally means “to finish” or “to put away.” However, when attached to a verb in the て-form (〜てしまう or ～でしまう), it expresses:

1. Completion of an action (to do something completely)
2. Regret or an unintended action (unfortunately, accidentally, or to one’s dismay)
   

1. Expressing Completion (Doing Something Completely)

This usage emphasizes that an action has been fully completed, often with a sense of finality.

Example Sentences:

• 宿題しゅくだいを やってしまった。(shukudai o yatte shimatta)
  (I finished my homework completely.)
• ケーキを全部ぜんぶ 食たべてしまった。(keeki o zenbu tabete shimatta)
  (I ate the entire cake.)
  

2. Expressing Regret or an Unintended Action

When 〜てしまう or ～でしまう is used in this way, it conveys a feeling of regret or an accident.

Example Sentences:

• 財布さいふを 忘わすれてしまった！(saifu o wasurete shimatta)
  (I forgot my wallet!)
• 友達ともだちの本ほんを なくしてしまった…。(tomodachi no hon o nakushite shimatta)
  (I lost my friend’s book…)
  

The Casual Form: 〜ちゃう / 〜じゃう

In casual speech, 〜てしまう is often shortened to 〜ちゃう (for て-form verbs) and 〜じゃう (for で-form verbs). This makes conversations sound more natural and fluent.

How to Form 〜ちゃう / 〜じゃう

Example Sentences

• ケーキを全部ぜんぶ 食たべちゃった！(keeki o zenbu tabechatta)
  (I accidentally ate the whole cake!)
• 宿題しゅくだい、忘わすれちゃった！(shukudai wasurechatta)
  (I forgot my homework!)
• 電車でんしゃ、行いっちゃった… (densha icchatta)
  (The train already left…!)
• 友達ともだちの本ほんを なくしちゃった。(tomodachi no hon o nakushichatta)
  (I lost my friend’s book…!)
  

When to Use 〜てしまう vs. 〜ちゃう

If you’re speaking to a teacher, in a work setting, or writing formally, use 〜てしまう. But if you’re chatting with friends, 〜ちゃう / 〜じゃう sounds more natural.

Summary

• 〜てしまう expresses completion or regret/unintended actions.
• In casual speech, 〜てしまう becomes 〜ちゃう and 〜でしまう becomes 〜じゃう.
• Use 〜てしまう in formal situations and 〜ちゃう / 〜じゃう in casual conversations.
  

Quick Quiz! 

1. Which is more formal: やってしまう or やっちゃう?
2. How would you say “I forgot my wallet!” in a casual way?
3. Convert 飲んでしまった to its casual form.
4. How would you say “I accidentally dropped my phone” using ちゃう?
5. What is the polite form of なくしちゃった?
6. If you’re writing an email at work, should you use 〜てしまう or 〜ちゃう?
7. Translate: “Oh no! I finished all the snacks!” using ちゃった.

Leave your answers in the comments below!

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