〜てやる: Doing For (Down) / Defiant Determination
What it means
You already know 〜てあげる ("do something for someone"). 〜てやる is the same idea — doing an action as a favor — but rougher and pointing downward. You use it for people of lower or casually-equal status, for animals, plants, and younger family members:
毎朝、犬を散歩させてやる。
まいあさ、いぬを さんぽさせて やる。
Every morning I take the dog for a walk.
For a pet → てやる is natural.
ヤッタンは弟に漢字を教えてやった。
ヤッタンは おとうとに かんじを おしえて やった。
Yattan taught his little brother kanji.
弟 (younger) → downward favor.
モチが困っていたら、手伝ってやるよ。
モチが こまって いたら、てつだって やるよ。
If Mochi's in trouble, I'll help him out.
Casual peer; friendly but blunt.
Note the plain verb 〜をやる ("to give to someone/something below") behind this: 花に水をやる ("water the plants"). 〜てやる extends that "giving downward" to actions.
How to form it
Take the て-form of a verb and attach やる. (Need a refresher? See the て-form.)
| Verb | て-form | + やる |
|---|---|---|
| 教える (teach) | 教えて | 教えてやる |
| 手伝う (help) | 手伝って | 手伝ってやる |
| 読む (read) | 読んで | 読んでやる |
| する (do) | して | してやる |
| 来る (come) | 来て | 来てやる |
Conjugate やる like a normal う-verb: やる → やった (past), やらない (negative), やろう (volitional).
The second use: determination and defiance
The same shape carries a completely different feeling when the action is about yourself. Here 〜てやる is a punchy, emotional "I'll do it — just watch me". It signals grit, a vow, sometimes spite. It overlaps with 〜てみせる ("I'll show you I can"):
今に見ていろ、絶対に成功してやる。
いまに みて いろ、ぜったいに せいこうして やる。
Just you wait — I'm going to succeed, no matter what.
Classic vow of determination.
あんな店、二度と行くものか。文句を言ってやる。
あんな みせ、にどと いく ものか。もんくを いって やる。
I'll never go to that shop again. I'm going to give them a piece of my mind.
言ってやる = defiant 'I'll tell them off.'
先生に勝ってやると、ヤッタンは心に決めた。
せんせいに かって やると、ヤッタンは こころに きめた。
'I'll beat the teacher,' Yattan resolved.
Inner resolve — not aimed at the teacher politely.
The trigger that tells you which meaning is in play is who benefits: if the action helps someone else (downward), it's a favor; if it's your own goal stated with force, it's determination.
More examples
子どもたちに本を読んでやるのが日課だ。
こどもたちに ほんを よんで やるのが にっかだ。
Reading books to the kids is part of my daily routine.
負けたままでは終われない。次は勝ってやる。
まけた ままでは おわれない。つぎは かって やる。
I can't end it on a loss. Next time, I'll win for sure.
モチが落ち込んでいたから、ごはんを作ってやった。
モチが おちこんで いたから、ごはんを つくって やった。
Mochi was feeling down, so I made him a meal.
Favor for a close friend — warm but rough register.
Common mistakes
- Using 〜てやる toward equals or superiors. It sounds rude or condescending. To a friend you respect, a senior, or a stranger, use 〜てあげる: 先生に教えてあげる is already a bit presumptuous — for a superior, rephrase entirely (e.g. お教えする).
- Mixing up the two meanings. 手伝ってやる to someone else = a (blunt) favor; 成功してやる about yourself = determination. The subject and beneficiary tell you which.
- Forgetting it's plain/rough. 〜てやる is casual male-leaning speech or inner monologue. There is no natural polite "〜てやります" for the determination sense — keep it plain.
- Treating it as neutral like 〜てあげる. Even as a favor, 〜てやる carries a top-down nuance. Don't use it when you simply want to sound kind; that's 〜てあげる's job.
Quick recap
- 〜てやる = て-form + やる, with two senses.
- Favor (downward): for pets, plants, younger family, casual peers — the rough version of 〜てあげる.
- Determination/defiance: "I'll do it, just watch" — 絶対にやってやる.
- Past = 〜てやった; it's rough/plain, easily rude to equals or superiors.
Your turn
Decide whether each 〜てやる is a downward favor or a vow of determination, and whether てあげる would be safer.
Start the 5-question drill →Frequently asked questions
What's the difference between 〜てやる and 〜てあげる?
Both mean doing something for someone, but 〜てやる is rougher and points downward — pets, plants, younger family, casual peers. 〜てあげる is the polite, neutral choice for friends, equals, and anyone you'd rather not sound condescending to.
How can the same 〜てやる mean both a favor and determination?
It's the beneficiary that decides. If the action helps someone else (downward), it's a favor: 手伝ってやる. If you state your own goal with force, it's determination: 絶対に勝ってやる ('I'll win, just watch').
Is 〜てやる rude?
It can be. Toward equals or superiors it sounds blunt or condescending. It's fine for pets, plants, young children, and close casual friends, and it's natural in tough-talk or inner resolve. When in doubt, use 〜てあげる.
Can I say 〜てやります politely?
For the favor sense it's possible but stiff and still top-down. For the determination sense, keep it plain (〜てやる) — that punchy, emotional feeling doesn't survive in polite form.