Learn Hardcore Japanese: yoru ha huro ni hairu kedo, asa ha syawaa dake ni suru. - At night I take a bath, but in the morning I only take a shower.

Japanese often drops the subject when it’s clear from context. In this sentence it most naturally means “I,” but depending on context it could also mean “you,” “we,” or people in general.

What does the particle は do after 夜 and 朝?

は marks the topic and is contrastive here: “As for nights … but as for mornings …” Putting は after time words like 夜 and 朝 is a common way to set up a contrast in habits.

Can I use 朝に or 夜に instead of 朝は and 夜は?

Use に for specific, scheduled times (e.g., 明日の朝に). For general habits, 朝/夜 usually appear without に, and は is perfect for contrast: 夜は… 朝は…. You could say 夜に in a specific one-time context, but for a habitual contrast, は is more natural.

Why does 風呂に入る mean “take a bath”? It literally looks like “enter the bath.”

That’s exactly the Japanese idiom: “to enter the bath” = “to take a bath.” Note the related but different verb お風呂を入れる, which means “to run/fill the bath.”

Why is the particle に used with 入る, not を or で?

入る is intransitive and takes に to mark the destination/space you enter, so 風呂に入る is correct. 風呂で入る and 風呂を入る are ungrammatical. If you talk about an action done in the bath (not entering it), you might use で with a different verb (e.g., 風呂で歌う).

What does けど do here? Is it casual? Are there alternatives?

けど means “but/though” and is casual. Politer choices are けれど(も) or が: 夜は風呂に入りますが、…. In conversation けど can even trail off at the end to soften a statement, but here it links two clauses normally.

What exactly does シャワーだけにする mean? Why に?

N + にする means “to choose/decide on N” or “to make it N.” With だけ, it means “limit it to only N,” so シャワーだけにする = “I’ll go with only a shower.” The に is required by the grammar of 〜にする.

Why not say シャワーを浴びる? Is シャワーだけにする different?

シャワーを浴びる is the straightforward “to take a shower.” シャワーだけにする highlights the decision/limitation (choosing “only a shower” rather than, say, a bath). You’ll also hear casual シャワーする, but シャワーを浴びる is the most standard.

Can I say 朝はシャワーだけだ or just 朝はシャワーだけ?

Yes. 朝はシャワーだけだ states the fact “In the morning it’s only a shower.” 朝はシャワーだけにする adds a nuance of choosing/deciding to keep it to a shower. In casual speech, 朝はシャワーだけ (dropping だ) is common and understood.

What’s the difference between だけ and しか here?

だけ is neutral “only.” しか must pair with a negative and emphasizes exclusivity: 朝はシャワーしか浴びない = “In the morning I don’t bathe in anything except a shower.” しか sounds a bit more restrictive/emphatic than だけ.

Is this sentence polite or casual? How would I say it politely?

It’s in plain (casual) style. A polite version is: 夜はお風呂に入りますけど、朝はシャワーだけにします。

Could I connect the two parts with て instead of けど?

You could say 夜は風呂に入って、朝はシャワーだけにする, which reads more like “and” rather than a clear contrast. けど/が makes the “but” contrast explicit and is more natural for this night-vs-morning pairing.

Can I use へ with 入る (e.g., 風呂へ入る)?

Modern, natural usage is 〜に入る, not 〜へ入る. Stick with 風呂に入る.

What’s the nuance difference between 風呂 and お風呂?

お風呂 adds a polite/honorific feel and is very common in everyday speech. 風呂 isn’t wrong; it’s just plainer/blunter. In polite contexts or when referring to someone else’s bath, お風呂 is safer.

Are spaces normal in Japanese writing? The sentence shows spaces.

Standard Japanese writing doesn’t use spaces between words; they’re added here for learners. In native text you’d see: 夜は風呂に入るけど、朝はシャワーだけにする。

Does the non-past (入る/する) here mean a habit?

Yes. The plain non-past with time expressions like 朝/夜 typically describes habitual routines. Depending on context it can also refer to a future plan, but here it reads as a general habit.