Learn Hardcore Japanese: kanozyo ha huro no ato, tyanto kigaete deru. - After the bath she properly gets changed before coming out.

It marks the topic: “as for her.” Using が instead would single her out as the specifically identified doer (answering “who?” or making a contrast), while は frames what follows as a statement about her in general.

Does 彼女 mean “she” or “girlfriend”?

Both. Without context, 彼女 can be read as “she” or “(my) girlfriend.” Japanese often avoids third-person pronouns; a name or role (e.g., 山田さんは, 母は) is common to prevent ambiguity.

Why is の used in 風呂のあと?

This is the pattern N のあと = “after N.” Here, 風呂のあと means “after the bath.” With verbs you use V-たあと (e.g., 食べたあと “after eating”).

Is 風呂のあと the same as 風呂の後で or 風呂の後に?

They’re all fine. のあと is a noun phrase; adding に/で marks the time point more explicitly, but is optional here. 後で alone is an adverb (“later”), while N のあと(に) attaches to the noun.

What nuance does ちゃんと add? Is it casual? Any synonyms?

ちゃんと means “properly, as one should, neatly,” often with a subtle normative tone. It’s common and slightly casual but widely acceptable. Near-synonyms: きちんと (tidy/proper, a bit more formal), しっかり (firmly/thoroughly; overlaps but not always interchangeable).

Does ちゃんと modify both 着替えて and 出る?

It scopes over the predicate that follows it, but in this sentence it most naturally emphasizes doing the changing properly. If you want to stress both, you can repeat it or rephrase (e.g., ちゃんと着替えて、ちゃんと出る).

What does the て-form in 着替えて do?

The て-form links actions, usually implying a natural sequence: “change (clothes) and then leave.” It can feel more immediate than てから, which explicitly means “after doing X, (then) Y.”

What’s the difference between 着替えて出る and 着替えてから出る?

着替えて出る bundles the actions smoothly in order. 着替えてから出る explicitly marks the first action as a prerequisite and can suggest a clearer boundary or slight gap between them.

Why doesn’t 着替える take an object here? Can I say 服を着替える or スーツに着替える?

着替える doesn’t need an object. You can say 服を着替える to mean “change out of (those) clothes,” and スーツに着替える to mean “change into a suit.” Generally, “X を着替える” = change out of X; “X に着替える” = change into X.

What exactly does 出る mean here? Leave what? How do I make it explicit?

出る is “to leave/exit” or “to go out,” and the origin is omitted here. To be explicit, add the place: 家を出る/家から出る (leave the house), 風呂を出る/風呂から出る (leave the bath/bathroom). If you mean “go out (for a while),” 出かける is often clearer.

Why is there no を or から after 出る in this sentence?

It’s just omitted because the origin is understood from context. Japanese frequently drops obvious elements. If you need precision, include A を出る or A から出る.

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

It’s plain/casual. Polite version: 彼女は（お）風呂のあと、ちゃんと着替えて出ます。 Past polite: 出ました; negative polite: 出ません.

Why is 出る in the non-past? Is this a habitual statement?

Yes. Japanese non-past covers both present and habitual/general statements. You can add いつも for emphasis: いつもちゃんと着替えて出る.

Can I say お風呂 instead of 風呂? Does it change the tone?

Yes. お風呂 adds a polite/softer tone and is very common in everyday speech. 風呂 is neutral to plain.

Could I topicalize 風呂のあと with は?

Yes: 風呂のあとは、彼女はちゃんと着替えて出る。 This puts focus on the time frame (“as for after the bath”).

Which kanji should I use for あと, and is the comma after あと necessary?

For “after (in time),” use 後: 風呂の後. Don’t use 跡 (trace/mark). The comma after あと is optional; it just marks a natural pause for readability.