Learn Hardcore Japanese: asita sensei ni syomei wo moraimasu. - I will get a signature from the teacher tomorrow.

The implied subject is the receiver: “I” (or “we”). With もらう, the sentence is from the receiver’s point of view. So the sentence means “I will receive a signature from the teacher tomorrow.” If you want to make the subject explicit, you can say: 私は明日先生に署名をもらいます。

Why is 先生 marked with に? Could I use から instead?

With もらう, the giver/source is marked by に or から.

に is common when the giver is a person you interact with directly: 先生に署名をもらう.
から emphasizes “from” as a source and works with people and institutions/things: 先生から/大学から/会社からもらう. Both 先生に and 先生から are fine here, with only a slight nuance difference (に feels a touch more direct/personal).

Why does 署名 take を?

もらう treats the received item as a direct object. The pattern is “Person に Thing をもらう.” Here, 署名 is the “thing,” so it takes を: 署名をもらいます.

Why is there no particle after 明日? Is 明日に wrong?

Time words like 明日, 今日, 来週 often function as adverbs without a particle. 明日に is generally not used to mean “tomorrow” in this kind of sentence. You do use に with specific clock times/dates (3時に, 1月1日に). 明日に can appear in special contexts (e.g., scheduling decisions: 明日にします), but not here.

Is the word order fixed? Can I move 明日 or 先生に around?

Japanese word order is flexible as long as particles are correct. Common and natural orders:

明日先生に署名をもらいます。 (very natural)
先生に明日署名をもらいます。 (fine)
署名を明日先生にもらいます。 (okay; puts focus on 署名) The verb もらいます should stay at the end.

Should it be 署名をもらいます or 署名してもらいます? What’s the difference?

Both are natural, with a nuance difference:

署名をもらいます: “I’ll receive the signature” (focus on the result/object).
署名してもらいます: “I’ll have (someone) sign (for me)” (focus on the action done for your benefit). For official documents, many speakers prefer 署名してもらいます; for autographs, サインをもらいます is very common.

Is this polite enough when talking about a teacher? Should I use いただきます?

もらいます is polite neutral, but when referring to receiving something from a higher-status person (like a teacher), the humble verb いただく is more respectful:

明日、先生にご署名をいただきます。
明日、先生に署名していただきます。 Adding ご to 署名 (ご署名) is a common honorific prefix for politeness.

How do I politely ask the teacher to sign?

Polite requests:

明日、署名していただけますか。
明日、ご署名いただけますか。
明日、署名をお願いできますか。 Even politer: …いただけませんか or …お願いしてもよろしいでしょうか。

How do I say the same idea from the teacher’s perspective using くれる/くださる?

Use くれる (plain) or くださる (honorific) with the teacher as the subject:

明日、先生が署名してくれます。 (The teacher will sign for me.)
明日、先生が署名してくださいます。 (More respectful.)

Can I say 先生の署名をもらいます?

Yes. 先生の署名をもらいます emphasizes the possession (“the teacher’s signature” as a noun phrase). 先生に署名をもらいます emphasizes the giver. Both are natural; choose based on what you want to highlight.

Does もらいます mean “will” (future) here?

Japanese non-past (〜ます/〜る) covers both present and future. The time word 明日 supplies the future meaning. For past, use もらいました; for “can receive,” use もらえます.

What if I couldn’t get the signature?

Use the negative past potential:

明日、先生に署名をもらえませんでした。 (I couldn’t get the signature from the teacher.) You can also use 〜てもらう: 署名してもらえませんでした。

Is 署名 the same as サイン? What about 判子/印鑑?

署名: formal “signature” (writing your name on official documents).
サイン: general “signature,” often an autograph from a celebrity; also used casually for signing.
判子/印鑑: personal seal/stamp used in Japan in place of a signature on many documents. Choose based on context. For an autograph: 先生のサインをもらいました. For an official form: 先生に署名してもらいました or ご署名をいただきました.

Is 署名をもらう natural Japanese?

Yes. It’s commonly used in contexts like documents and petitions: 書類に必要な署名をもらう. If you want to emphasize the act, 署名してもらう is also very common.

How would I read/pronounce the sentence?

あしたせんせいにしょめいをもらいます.

Should I add 私は at the start?

Only if you need to clarify the subject or contrast with someone else. Otherwise it’s usually omitted and understood from context. If you do add it: 私は明日先生に署名をもらいます。

Is it okay to use the causative, like 先生に署名させます?

Avoid that here. 〜させる means “make/let someone do,” which can sound coercive (“I’ll make the teacher sign”). To express “have someone do (for me),” use 〜てもらう: 先生に署名してもらいます.

Can I use は for emphasis, like 先生には?

Yes. Adding は creates contrast/topic emphasis:

先生には署名をもらいます。 (As for the teacher, I’ll get a signature [implying contrast with others].)
明日は先生に署名をもらいます。 (As for tomorrow…) Use it when you want to highlight or contrast that element.

Why are there spaces between the words?

They’re just for learner clarity. Standard Japanese writing doesn’t use spaces: 明日先生に署名をもらいます.