てしまう・ちゃう・じゃう - Grammar Discussion

to do something by accident
to finish completely


  • Verb[ ] + しまう or ちゃう
  • Verb[ ] + しまう or じゃう

[食べて しまう or 食べ ちゃう ・死んで しまう or 死ん じゃう ]

[Also used when something happens inadvertently or something “ends up” in a certain state]

View on Bunpro

I’m not quite sure what I’m doing wrong here?

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Hey :bowing_man:

It should be 忘れちゃった instead of 忘れてちゃった。
The て form is used, but て itself is removed and ちゃう is attached to what is left from it.

It goes like this:

わすれるーmake て form→忘れてーremove て→忘れーadd ちゃう→忘れちゃうーpast form→忘れちゃった

The structure section was a bit unclear, so I have fixed it:

I hope it helps!
Cheers :+1:


Ah that explains what went wrong, thank you so much! All the examples used てしまう as well, so it got quite confusing :sweat_smile: Maybe have some examples alter readings in this case, or maybe alter readings at random even :open_mouth:

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(Please let other people’s subsequent hearts dictate whether I’m alone on this, but…)

I really don’t like the mixing of this grammar point with the volitional, in the example problem
今日は冬休みの宿題を全部 してしまおう.

I’d much rather practice this new grammatical form on its own, and then mix with other grammatical elements like volitional, later on, when I feel more comfortable.

Or - at very least - I’d like to humbly request a “soft error” here, reminding me that (inexplicably) this question is asking for a variation what’s been taught in the ‘Grammar Info’ section.

Thank you for all you do.

Again… could be just me. Some brains probably appreciate the mixing of lower-level grammar points.


What is the English translation of the sentence? I would say that if the translation says something along the lines of ‘let’s’ then it would be OK because the aim of BunPro is to build on already learned grammar by mixing it into sentences in new grammar.

I think this is a good idea yeah.

@chrischriskurisu Thank you for your feedback. As @matt_in_mito mentioned, the goal of Bunpro is to use previously studied grammar in sentences so that they both build off of what you have already learned and introduce you to new contexts/situations where that particular grammar point can be used.

The casual volitional is introduced in Lesson 4, while てしまう does not appear until Lesson 8, so unless you are adding entire lessons to your reviews daily, this should give you plenty of time to familiarize yourself with the volitional and how it is used.

Before you type your answer, the hint “[casual + volitional]” is shown in the answer blank (in the Japanese sentence). If you have all of your hints turned on, you should also be seeing "[casual・volitional (can also be translated as “let’s”)].

If you type in the plain form (dictionary form) or the polite ます-form, you will get the hint “Think ‘will’ (volitional).”

We try our best to guide you along if you happen to forget a certain form, rather than marking you wrong outright. We are always trying to improve how the system works by making it more intuitive and your feedback helps us do that. Cheers!

My apologies. I wasn’t clear that I am attempted to practice the ~ちゃう form. しまう seems like a piece of cake, so I’m practising the variations.

So I typed しちゃう… which of course is wrong because it doesn’t account for volition. My bad.
I can see that this is an error, but I don’t know if it’s because:

  • One simply cannot express 〜ちゃう with する?
  • One cannot change 〜ちゃう to make it volitional.

So… this could totally be my bad. But any time I find myself in a situation where I think “I’m wrong but I don’t know why”, I can’t help but wonder if it’s me & my own failings, or if the question itself could use some tweaking.

Again… if you never see any hearts or upvotes for me comment, then you’ll know I’m an outlier and this is really a non-issue. Sorry again for the bother.




I see! That’s my bad for not realizing that you could have been trying different variations.

If you have to ask these types of questions then we are not doing a good enough job of explaining why you got an answer wrong (or in this case, not providing a hint at all). I have gone back through the questions to add that てしまう and 〜ちゃう variations are both acceptable in this case but sound a little more direct/final. That being said, we would still like you to practice the volitional form here to help reinforce what you have previously learned.


@Pushindawood Thank you for your feedback. Okay, I will continue to practice the volitional form.

Thank you for your consideration with updating the responses to 〜ちゃう based answers. I appreciate your open mindedness and dedication. I realize that there can be countless permutations of error handing, since grammar is not always a “yes or no” kind of thing. So thank you again.

Hi! I came here after being tested with the same phrase that @chrischriskurisu mentions: 今日は冬休みの宿題を全部 してしまおう.

When I’ve seen the correct answer (after giving up after trying with してしまう and しちゃう), I was very surprised and thought it was a bug, after re-reading the grammar explanation for this item and seeing that this しまおう form don’t appear anywhere in the meaning explanation or the examples (and since I’ve following a different grammar path, it’s literally the first time I’ve seen it).

I think is quite confusing, since the only way to proceed is to fail it, and then search where in Bunpro is the grammar point that explains that volitional, not either having a clue of where to search. (I’m really just trying to find it in the “grammar search” with しまおう, まおう and no luck …)

Maybe a solution to this, if one item will use test sentences that use other grammar points, could be to indicate it in the study section, and give a reference to it, so you can know that in order to pass the sentences you need to study that other point first.

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Hi guys! Just one quick question. Anyone knows why in this present continuative form the
contracted てしまう is like this: おいていっちゃう? Shouldn´t it be おいていちゃう because the て
form of いる is いて? Thanks!

@kousei22 Hey! おいていっちゃう is the てしまう short-form conjugation of 置いて + 行く, 置いて行っちゃう - to leave behind. Cheers!

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Ohh! I got confused between 行く and いる! Many thanks for clarifying!

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According to the linked Japanese Ammo video, てしまう is considered formal and is most likely to be heard in literature or songs. Shouldn’t 遅れちゃう be the only correct answer here?

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Hey and long time no see!

You can change てしまう to ちゃう(じゃう) in casual language, but you doesn’t have to do that. So either are fine in this case.




Can someone explain why we should use volitional here?
今日は冬休みの宿題を全部 してしまおう

English translation doesn’t imply any volitional

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Hey @Christophegand !

The volitional form is used here to make the sentence sound more natural. When natives try to talk themselves into doing something, they will often times use the volitional form to motivate themselves. The nuance this sentence has is, ‘Hey me! Let’s finish all the homework for winter break today! (I shall finish all the homework for winter break today)’. It doesn’t necessarily need to be in the volitional form, but in this sentence, the speaker is talking to themself, it is a little more natural to use the volitional form. We have changed the ‘will’ to ‘shall’ so that the English translation implies volitional. I hope that answers your question!

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Could someone please explain why the causative (せる・させる) is used in this lesson’s examples?

Let’s completely finish my homework before I start playing video games!

Aoki senpai, let’s completely finish the report that our boss has asked us to do before work is over.

If I understand correctly, 終わらせる and させる are the causative forms of 終わる and しる, respectively. Why not use the plain form of the verbs instead?

Thanks in advance if anyone sees this. :slight_smile:

Hey @ResFort !

Although 終わる and 終わらせる can be translated as ‘to finish’, 終わらせる has the nuance of ‘to make (something) come to an end’, so, 終わらせてしまう and 終わってしまう have very different meanings. 終わらせてしまう translates as ‘I am going to make myself finish (something) completely’, while 終わってしまう translates as ‘unfortunately, it ends/finishes’. Because of this difference in nuance and translation, using the plain forms of 終わる and する makes the sentences sound very unnatural.

For example, ゲームを始める前に宿題を終 わってしまおう。Sounds like ‘Let’s unfortunately my home work finished before I start playing video games’. The Japanese sentence sounds as unnatural as the English sentence.

We hope this clears it up!

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