Learn Hardcore Japanese: asita ha hayaku okinakereba narimasen.

Here, 明日 just functions as a time expression without being marked as the topic. Both are correct. Using は slightly emphasizes “tomorrow” as the main frame of the sentence.

You would not normally use が here; it wouldn’t be natural to treat 明日 as the grammatical subject.

Why is it 早く and not 早い?

早い is an adjective (“early”).
早く is its adverb form (“early” in the sense of “early-ly,” i.e., modifying a verb).

早い modifies nouns:
- 早い朝 – an early morning
早く modifies verbs:
- 早く起きる – to get up early

In this sentence, 早く modifies the verb 起きる (“to get up”), so the adverb form 早く is required, not the adjective 早い.

What is the difference between 早く and 速く?

Both are read はやく (hayaku), but they are usually used differently:

早く – “early” in time:
- 早く起きる – get up early
- 早く帰る – go home early
速く – “fast/quickly” in speed:
- 速く走る – run fast
- 車が速く動く – the car moves fast

In 明日は早く起きなければなりません, it’s about time (early in the day), so 早く is used.

Where is the subject “I” in this sentence? Why isn’t it written?

Japanese often omits the subject when it is clear from context.

明日は早く起きなければなりません。
Literally: “As for tomorrow, (if [someone] doesn’t get up early, it won’t do).”
In normal conversation, it’s understood as “I” (or “we”) from context.

You could explicitly say:

私は明日早く起きなければなりません。 – I have to get up early tomorrow.

But adding 私 is often unnecessary and can sound stiff or overly explicit if the subject is obvious.

What does 起きなければなりません literally mean?

It’s built from:

起きる – to get up / wake up
起きない – negative form: “don’t get up”
起きなければ – “if (I) don’t get up” (negative conditional)
ならない → なりません – “will not do / is not acceptable” (polite negative)

So 起きなければなりません literally means:

“If I don’t get up, it will not do.”

Functionally, this is how Japanese expresses obligation:
→ “must get up / have to get up.”

How does 〜なければなりません compare with must / have to in English?

〜なければなりません is a fairly formal / stiff way to say “must / have to.”

早く起きなければなりません。
≈ “I must get up early.” / “I have to get up early.”

In conversation, many people use softer or shorter forms instead (see below), but grammatically this is the standard polite way to say “must.”

Is there a more casual way to say 起きなければなりません?

Yes. Common alternatives are:

起きなければならない。
– Plain (non-polite) form.
起きなくてはいけません。
– Also polite, similar meaning.
起きないといけません。
– Very common in speech.
起きなきゃ。 (short for 起きなければ)
– Casual, often said with a trailing tone:
“(I) gotta get up.”
起きないと。 (short for 起きないといけない)
– Another casual “I have to get up.”

All of these can imply obligation; choice depends on politeness and formality.

What is the difference between 〜なりません and 〜いけません?

Both appear in obligation patterns:

起きなければなりません。
起きなくてはいけません。

Core meaning is the same: “must / have to.”

Nuance:

〜なければなりません
- Sounds a bit more formal / textbook-like.
- Often seen in writing, explanations, official speech.
〜なくてはいけません / 〜ないといけません
- More natural in everyday conversation.
- Slightly softer and more common in spoken Japanese.

For a learner, you can treat them as essentially equivalent in meaning.

Why is it 明日 with は, and not 明日に? Don’t time expressions often take に?

Time expressions can take に, but not always, and 明日 is often used without it.

Specific time points can take に (optional in many cases):
- 3時に行きます。 – I’ll go at 3 o’clock.
- 明日(に) 行きます。 – I’ll go tomorrow. (に is optional and often dropped.)

In this sentence:

明日は – は marks the topic, not time.
You could also say 明日早く起きなければなりません。 with no particle after 明日.

明日に早く起きなければなりません is unnatural; に here would make it sound like “on/for tomorrow, I must get up early,” which isn’t how Japanese expresses this idea.

Can I change the word order, like putting 早く before 明日?

Natural options include:

明日は早く起きなければなりません。
明日早く起きなければなりません。 (no は, just adverbial 明日)

These are both fine.

But something like:

早く明日は起きなければなりません。

is unnatural; the topic 明日は normally comes near the beginning, and the adverb 早く naturally goes just before the verb 起きる or before the whole 起きなければなりません chunk:

明日は早く起きなければなりません。 (most natural ordering)

How do I say “I don’t have to get up early tomorrow” instead?

Japanese does not negate obligation by simply negating なければならない.
Instead, a different pattern is used:

明日は早く起きなくてもいいです。
– I don’t have to get up early tomorrow.
(Literally: “It’s okay even if I don’t get up early tomorrow.”)

Or:

明日は早く起きる必要はありません。
– I don’t need to get up early tomorrow.

Avoid:

✕ 明日は早く起きなければなりませんじゃない
as a direct equivalent of “don’t have to.” That sounds like “It’s not that (I) must,” which is different in nuance and not the natural way to express “don’t have to.”

How would I say this sentence in plain (non-ます) form?

Polite form (original):

明日は早く起きなければなりません。

Plain equivalents:

明日は早く起きなければならない。
More conversational: 明日は早く起きないといけない。
Very casual/short: 明日は早く起きなきゃ。 / 明日は早く起きないと。

All keep the same basic meaning: “I have to get up early tomorrow,” but with less politeness/formality.