Once you can build a て-form, a whole toolbox opens up: attach a helper verb to it and you get a new shade of meaning — do something in advance, end up doing it, try doing it, keep on doing it. These helpers are called 補助動詞（ほじょどうし, hojodōshi）, "auxiliary verbs." Each one started life as an ordinary verb (置く "place," 見る "see," 行く "go"), but as a helper its literal meaning has worn away, leaving behind pure grammar — aspect or the speaker's attitude. This page is the map of the whole family, so you can see how the pieces fit before drilling into each one.
What a 補助動詞 is
A 補助動詞 is a verb that has stopped meaning what it used to mean and now just modifies the verb in front of it. The pattern is always the same: main verb (て-form) + helper. The main verb carries the real action; the helper adds a layer on top.
とりあえず、ビールを買っておこう。
toriaezu, bīru o katte okō
For now, let's go ahead and buy some beer (for later).
Here 買う "buy" is the real action; おく (from 置く "place") no longer means "place" at all — it adds the sense "in advance, so we're set." That layering is what every member of the family does.
The family at a glance
| Auxiliary | Origin verb | Grammatical meaning | Example |
|---|---|---|---|
| 〜ている | いる (be / exist) | progressive / resulting state | 待っている "is waiting" |
| 〜てある | ある (be / exist) | resultant state (prepared) | 置いてある "is (left) placed" |
| 〜ておく | 置く (place) | do in advance | 買っておく "buy ahead" |
| 〜てしまう | しまう (put away) | completion / regret | 食べてしまう "eat it all up" |
| 〜てみる | 見る (see) | try doing | やってみる "give it a try" |
| 〜ていく | 行く (go) | motion / change away | 増えていく "keep increasing" |
| 〜てくる | 来る (come) | motion / change toward | 分かってくる "come to understand" |
| 〜てあげる | あげる (give) | do for someone (outward) | 教えてあげる "teach (for them)" |
| 〜てくれる | くれる (give me) | do for me (inward) | 手伝ってくれる "help me out" |
| 〜てもらう | もらう (receive) | get someone to do | 直してもらう "have it fixed" |
The first four rows add aspect (how the action sits in time — ongoing, prepared, completed). The middle rows add direction in space or time. The last three — the giving-and-receiving helpers — add the social direction of a favor; they're covered under Verbs-advanced.
The kana tell: how you can see it's an auxiliary
Here is the single most useful insight on this page. Japanese writing signals grammaticalization orthographically. When one of these verbs is used literally, it keeps its kanji; when it becomes an auxiliary, it drops to kana. The script itself tells you whether the verb still means what it says.
| Literal verb (kanji) | As auxiliary (kana) |
|---|---|
| 見る "to look at" | 〜てみる "try doing" |
| 置く "to place" | 〜ておく "do in advance" |
| 行く "to go" | 〜ていく "keep / go on" |
| 来る "to come" | 〜てくる "come to / begin" |
| いる／ある "to be, exist" | 〜ている／〜てある "aspect" |
One honest caveat: 〜ていく and 〜てくる are sometimes still written 〜て行く／〜て来る, and you'll see both in the wild. Official style guidance (公用文, government writing standards) recommends kana for the auxiliary use, and that's the modern default — but this pair is the least consistent, so don't be surprised to meet the kanji version.
Reading the helper literally is the trap
The number-one error for English speakers is to translate the helper by its origin. It never works, because the origin meaning is gone.
宿題を全部やってしまった。
shukudai o zenbu yatte shimatta
I've finished all my homework. (or, ruefully: I ended up doing it all.)
しまう here is not "put away" — it's completion, sometimes with a tinge of regret (see 〜てしまう).
新しいラーメン屋、もう行ってみた？
atarashii rāmen-ya, mō itte mita?
Have you tried the new ramen place yet?
みる is not "see" with your eyes — it's "try and find out how it goes" (see 〜てみる).
この技術は、これからも進化していくだろう。
kono gijutsu wa, kore kara mo shinka shite iku darō
This technology will surely keep evolving from here on.
いく is not "go" anywhere — it's a change projecting into the future.
The rest of the family, in one line each
締め切りをすっかり忘れてしまった。
shimekiri o sukkari wasurete shimatta
I completely forgot the deadline (and now I regret it).
友達が引っ越しを手伝ってくれた。
tomodachi ga hikkoshi o tetsudatte kureta
A friend helped me out with the move (a favor to me).
先生に作文を直してもらった。
sensei ni sakubun o naoshite moratta
I had my teacher correct my essay for me.
冷蔵庫にケーキが入れてあるよ。食べていいよ。
reizōko ni kēki ga irete aru yo. tabete ii yo
There's cake put away in the fridge. Feel free to have some.
Each is the same recipe — て-form plus a light helper that adds aspect, direction, or attitude — and each has its own page for the details.
How this differs from English
English does have loosely comparable "light verb" helpers — "go ahead and buy it," "end up forgetting," "try eating," "keep growing" — so the idea of a helper that adds nuance isn't foreign. What's different is that Japanese systematizes it: one productive slot after the て-form, filled by a small closed set of verbs, each grammaticalized to a fixed nuance. English scatters the same jobs across "go ahead," "end up," "manage to," and bare "-ing," with no unifying pattern. Once you internalize the slot, you stop learning ten idioms and start seeing one system.
Common mistakes
Writing the auxiliary in kanji. The kana spelling marks the grammatical use; the kanji spelling forces the literal reading.
❌ ちょっと食べて見る。
chotto tabete miru
Reads as 'eat, then look at (it)' — the kanji 見 keeps the literal 'see.'
✅ ちょっと食べてみる。
chotto tabete miru
I'll give it a taste (try eating it).
Kanji again — with 置く. Same trap: 置く in kanji means physical placing.
❌ ビールを買って置く。
bīru o katte oku
Reads as 'buy the beer and set it down' — the kanji 置 blocks the 'in advance' sense.
✅ ビールを買っておく。
bīru o katte oku
Buy the beer in advance.
Reading てしまう as "put away." The origin meaning is gone; it's completion or regret.
❌ 皿を割ってしまった。
sara o watte shimatta
Do NOT read this as 'I broke the plate and put it away' — しまう is not literal here.
✅ 皿を割ってしまった。
sara o watte shimatta
I broke the plate (darn it) — completion with regret, no 'putting away.'
Attaching the helper to the wrong form. These helpers glue onto the て-form, not the dictionary form or the ます-stem.
❌ ちょっとやるみる。
chotto yaru miru
Incorrect — needs the te-form やって, not the dictionary form やる.
✅ ちょっとやってみる。
chotto yatte miru
I'll give it a try.
Mixing up which helper you want. Preparing an action (ておく) and describing the state it leaves (てある) are close cousins that beginners blend — see 〜ておく vs 〜てある to keep them apart.
Key takeaways
- A 補助動詞 is a former full verb, now grammaticalized, that attaches to a て-form and adds aspect, direction, or attitude.
- The core set: 〜ておく (advance), 〜てしまう (completion/regret), 〜てみる (try), 〜ていく／〜てくる (motion & change), 〜ている／〜てある (aspect), plus the favor helpers 〜てあげる／〜てくれる／〜てもらう.
- The kana tell: literal use keeps kanji (見る, 置く, しまう); auxiliary use drops to kana (てみる, ておく, てしまう) — the script flags the grammaticalization.
- Never translate the helper by its origin — てみる isn't "see," てしまう isn't "put away."
Now practice Japanese
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- 〜ておく／〜とく: Doing in AdvanceN3 — How 〜ておく (from 置く 'to place') means doing something in advance or leaving it done for later benefit — plus the casual 〜とく／〜どく and the useful やめておく 'I'll pass.'
- 〜てしまう／〜ちゃう: Completion & RegretN3 — How te-form + しまう seals an action as finished — reading it as satisfying completion or as an 'oops, irreversibly' regret, plus the casual 〜ちゃう／〜じゃう contractions and their voicing split.
- 〜てみる: Try Doing (and See)N3 — How te-form + みる means to do something on a trial basis to find out what it's like — a genuine attempt that is actually carried out, not the mere 'trying to' of struggling English.
- 〜ていく／〜てくる: Motion with an ActionN3 — How te-form + いく／くる attaches physical direction to an action — いく moves away from the speaker, くる moves toward them and often frames a there-and-back round trip anchored to where the speaker stands.