Learn Hardcore Japanese: asita ha syukudai wo yarimasu.

So 明日 is not the grammatical subject; it's the topic. The sentence is framed around “tomorrow,” and then we’re told what will happen regarding tomorrow.

Because は can also carry a contrast nuance, the sentence can imply something like:

“As for tomorrow (at least), I will do homework (maybe not on other days).”
But without context, it’s simply “Tomorrow, I will do homework.”

Why isn’t there a word for “I” in the sentence?

Japanese often omits the subject if it’s clear from context.

In English, you must say “I will do my homework tomorrow.”
In Japanese, if it’s obvious that you are talking about yourself, just leaving out 私 (I) is natural:
明日は宿題をやります。 = “(I) will do my homework tomorrow.”

If needed, you can say:

私は明日は宿題をやります。
but this sounds heavy unless you really want to emphasize me.

Why is は pronounced “wa” here instead of “ha”?

When は is used as a particle (topic marker), it is always pronounced “wa”, not “ha.”

In words: 花 (はな, hana) – “flower” → は is read “ha.”
As particle: 明日は (あしたは, ashita wa) → は is read “wa.”

Same writing (は), different reading depending on function. This is just a special rule of modern Japanese spelling.

What role does を play after 宿題, and why not が or は?

を marks the direct object of the verb – the thing the action is done to.

宿題をやります。
→ “(I) will do homework.”
→ 宿題 = the thing being done → direct object → gets を.

If you used:

宿題がやります – wrong: が usually marks the subject; this would sound like “The homework will do (something).”
宿題はやります – possible, but different: 宿題 becomes the topic/contrast:
“As for homework, I will do it (but maybe not something else).”

So を is correct here because homework is what you do, not the topic or subject.

What’s the difference between 宿題をやります and 宿題をします?

Both can mean “do homework,” but there’s a nuance:

宿題をする
- The most standard/neutral expression.
- Common in textbooks, schools, and polite conversation.
宿題をやる
- Slightly more casual/colloquial.
- In plain form (やる) it can sound a bit rough or boyish depending on context.
- In ます-form (やります), it is still grammatically polite, but する feels more neutral and “safe” in formal situations.

So:

With friends: 今日、宿題やる？ – very natural.
In a polite context: 今日は宿題をします。 is a bit more typical than やります.

Is やります polite or casual?

やります is the polite -ます form of やる.

Dictionary/plain form: やる → casual.
Polite form: やります → polite.

So the sentence 明日は宿題をやります。 is polite overall.
However, compared to します, やります still carries a slightly more informal/colloquial flavor in terms of word choice, even though the form is grammatically polite.

Why does やります (present tense) mean “will do” and not just “do”?

Japanese verbs mainly distinguish past vs non-past, not present vs future.

やりました = past (“did”).
やります = non-past:
- present (“do / usually do”)
- or future (“will do”), depending on context.

When you add a future time word like 明日 (tomorrow), the non-past form naturally gets a future meaning:

明日は宿題をやります。
→ “I will do my homework tomorrow.”

Without a time word, it could mean a habitual action:

毎日宿題をやります。
→ “I do homework every day.”

Can I change the word order? For example, can I say 宿題を明日やります?

Yes, Japanese word order is flexible as long as the verb stays at the end.

All of these are possible:

明日は宿題をやります。
→ Topic: tomorrow. Natural, neutral.
宿題を明日やります。
→ Slight emphasis on 宿題 first; sounds like you’re focusing on homework, then specifying tomorrow.
明日、宿題をやります。 (no は)
→ Just “Tomorrow, I’ll do homework,” without explicitly making 明日 the topic.
宿題は明日やります。
→ Topic/contrast on 宿題: “As for the homework, I’ll do it tomorrow (maybe other things at other times).”

Meaning is similar, but topic and emphasis change with order and particles.

What is the difference between 明日は宿題をやります and 明日宿題をやります (without は)?

明日は宿題をやります。
- 明日 is marked as the topic.
- Can carry a contrast nuance:
  “As for tomorrow, I’ll do homework (maybe not on other days).”
明日宿題をやります。
- 明日 is just a time expression; no explicit topic marking.
- Sounds like a straightforward statement: “Tomorrow I’ll do homework,” with less built-in contrast.

Both are correct; は adds a bit of topic/contrast flavor.

Why is there no particle like に after 明日? Can I say 明日に宿題をやります?

Time words like 明日 (tomorrow), 今日 (today), 昨日 (yesterday) usually do not need a particle when they just indicate when something happens.

So:

明日宿題をやります。 – natural.
明日は宿題をやります。 – also natural (with topic は).

明日に宿題をやります is generally unnatural in standard Japanese.

You might see 明日に only in special structures like:

明日にします。 – “Let’s make it tomorrow.”
or
明日には宿題をやります。 – “By tomorrow I will do my homework,” where には adds emphasis or “by” nuance.

Are particles like を and は always necessary? Can I drop を in casual speech?

In standard textbook Japanese, you should keep the particles:

明日は宿題をやります。 – correct and clear.

In very casual conversational Japanese, especially when context is strong, people sometimes drop particles:

明日宿題やる。
明日、宿題やる？

This is common in speech between friends, but:

It’s less appropriate in writing or polite situations.
As a learner, it’s safer to use particles correctly first, then gradually get used to hearing them dropped.

How do you read each part, and is it okay to write しゅくだい in hiragana instead of 宿題?

Readings:

明日 – usually あした (ashita); sometimes あす (asu) in more formal contexts.
は (particle) – wa.
宿題 – しゅくだい (shukudai).
を – o (often pronounced very lightly, almost like wo).
やります – yarimasu.

Writing:

宿題 is the standard kanji.
Writing it in hiragana (しゅくだい) is not wrong, just more childish-looking or informal.
In normal adult writing, 宿題 is preferred; beginners’ materials may use hiragana to ease reading.

How would I say “I will not do homework tomorrow” and “Will you do homework tomorrow?” using this sentence pattern?

Using やります as the base:

Negative:
- 明日は宿題をやりません。
  → “I will not do homework tomorrow.”
Question:
- 明日は宿題をやりますか。
  → “Will you do homework tomorrow?”

In speech, you’d also use a rising intonation on か (or even omit か in casual speech and just raise your voice: 明日宿題やる？).