Learn Hardcore Japanese: kanozyo ha zyuudenki wo itumo kaban ni irete oku.

〜ておく means “do something in advance and leave it that way (for convenience/just in case).” So 入れておく is “to put it in and keep it there (prepared).” It’s not just “put,” but “put and leave/keep,” often with a sense of preparation.

How is 入れておく different from just 入れる?

入れる: simply “to put/insert.”
入れておく: “to put (now) so it will be there later,” implying preparation or maintaining that state.

What’s the difference between 入れておく, 入れている, 入っている, and 入れてある?

入れておく: the actor proactively puts it in and leaves it there for future convenience (habit or preparation).
入れている: transitive progressive/habitual; “(she) keeps it there” as her ongoing habit.
入っている: intransitive resultant state; “it is in there” (focus on location, no actor).
入れてある: resultant state from someone’s intentional action; “it has been put (and is there).” Typically used like かばんに充電器が入れてある (don’t usually name the agent).

Why is を used after 充電器?

Because 入れる is a transitive verb and 充電器 is the direct object: you “put a charger” into something, so the object takes を.

Why is に used after かばん?

に marks the target location or container with verbs of putting/placing. With 入れる, the container takes に: かばんに入れる = “put into the bag.”

Can I use へ instead of に with 入れる?

No. へ marks direction of movement, but with “put into (a container)” you use に. So かばんへ入れる is unnatural; use かばんに入れる.

Can I say かばんの中に instead of かばんに?

Yes. かばんの中に emphasizes “inside the bag.” かばんに already implies “into the bag,” but 中 makes it explicit.

Where can いつも go in the sentence?

Common, natural positions include:

彼女はいつも充電器をかばんに入れておく。
彼女は充電器をいつもかばんに入れておく。 Both are fine. Putting いつも early (after the topic) is most typical. Avoid splitting the verb phrase awkwardly.

Is this sentence casual or polite? How do I make it polite?

It’s plain (neutral) style. Polite version: 彼女は充電器をいつもかばんに入れておきます。 Past polite: 入れておきました. Negative polite: 入れておきません.

Could I drop 彼女は or replace it with a name?

Yes. Japanese often omits known subjects: 充電器をいつもかばんに入れておく。 Using a name or title instead of 彼女 is common and often more natural in conversation.

Does 彼女 always mean “she,” or can it mean “girlfriend”?

Both. 彼女 can mean “she” or “girlfriend.” Context clarifies. If there’s a risk of confusion, use the person’s name/title instead.

Why isn’t “her” explicitly marked in かばん?

Japanese often omits possessives when obvious from context. かばん here is understood as “her bag.” If needed, say 彼女のかばんに.

What’s the reading and nuance of 充電器? Is it the same as a power bank?

Reading: じゅうでんき (juudenki), meaning “charger.”
A power bank is typically モバイルバッテリー. 充電器 usually means the adapter/cable used to charge devices.

Can I use バッグ instead of かばん?

Yes. バッグ is fine and common. かばん (often written in kana) is a general “bag,” slightly broader/neutral.

How do I say this in the past or negative?

Past (plain): 入れておいた (She kept/put it in advance).
Negative (plain): 入れておかない (She doesn’t keep it there in advance).
Past negative (plain): 入れておかなかった. Polite: 入れておきました / 入れておきません / 入れておきませんでした.

Is the colloquial contraction 入れとく OK?

Yes, in casual speech 入れておく → 入れとく, past 入れといた, negative 入れとかない. Avoid in formal writing.

Could I topicalize other parts, like 充電器は or かばんには?

Yes, to shift emphasis:

充電器はいつもかばんに入れておく。 (As for the charger, [she/I] always keep it in the bag.)
かばんには充電器をいつも入れておく。 (As for the bag, a charger is always kept in it.) Avoid overusing multiple は topics unless context calls for it.

How does いつも compare with よく or たいてい here?

いつも: always, without exception (or very close to it).
よく: often/frequently (less than always).
たいてい: usually/mostly (habitual but allows exceptions).

What’s the transitive–intransitive pair here, and why does it matter?

Transitive: 入れる (put something in) → takes を: 充電器を入れる.
Intransitive: 入る (something goes/is in) → subject with が: 充電器が入る/入っている. Choosing the right one affects particles and the viewpoint (actor vs state).

Is there any orthography nuance with おく?

As an auxiliary, おく is usually written in hiragana (入れておく). The standalone verb “to place” is 置く. In this sentence おく is the auxiliary “do in advance,” not the main verb “to place.”