Learn Hardcore Japanese: asita no tyourei de mizikai zikosyoukai wo simasu. - Tomorrow I will give a short self-introduction at the morning assembly.

So instead of saying “at the morning assembly tomorrow” as in English, Japanese bundles it into one noun phrase: 明日の朝礼 (“tomorrow’s morning assembly”).

Why is で used in 朝礼で instead of に?

で marks the place or setting where an action happens.

朝礼で短い自己紹介をします。
→ “I will do a short self-introduction at the morning assembly.”

Here, 朝礼 is treated as the occasion / setting for the action. That’s what で is good at: “in/at (as the place where something is done).”

Using に with 朝礼 in this sense would sound unnatural:

朝礼に自己紹介をします is not how native speakers express “introduce myself at the morning assembly.”

に is fine for:

points in time: ８時に始まります。 = It starts at 8.
destinations/targets: 学校に行きます。 = I go to school.

But for “I do X at that event/place,” で is the natural choice:

学校で勉強します。 = I study at school.
会議で発表します。 = I’ll present at the meeting.
朝礼で自己紹介します。 = I’ll introduce myself at the morning assembly.

What exactly is 朝礼 (ちょうれい)? Is it just “morning meeting”?

朝礼（ちょうれい） is a fixed cultural term:

In schools: a short gathering in the morning where announcements are made, sometimes with the principal or homeroom teacher speaking, greetings, etc.
In companies: a brief morning assembly where the team or the whole company gathers to share announcements, goals, or greetings.

It’s close to “morning assembly” or “morning briefing”, but it tends to have a set, somewhat formal feel in Japanese school/work culture.

What does the particle を do in 自己紹介をします?

を marks the direct object of the verb.

自己紹介 = self-introduction (a noun)
～をする / ～をします = to do (something)

So:

自己紹介をします。
= “(I) will do a self-introduction.”

Structure:

[object] + を + します
→ 自己紹介 (self-intro) is what you “do”.

Why is します (present tense) used to talk about the future?

Japanese doesn’t have a dedicated future tense. The non-past form (します, 行きます, etc.) covers both:

present / habitual actions:
- いつも朝ごはんを食べます。= I always eat breakfast.
future actions / plans:
- 明日、映画を見ます。= I will watch a movie tomorrow.

In this sentence:

明日 (“tomorrow”) tells you it’s about the future.
します is the standard polite non-past form.

So:

明日の朝礼で短い自己紹介をします。
= “I will do a short self-introduction at the morning assembly tomorrow.”

If you wanted to stress intention, you might say:

自己紹介をするつもりです。 (I intend to introduce myself.)
But for a simple statement about something scheduled or planned, します is completely natural.

Why isn’t “I” (私は) written in the sentence?

Japanese very often omits the subject when it’s obvious from context.

In English you must say “I will do a self-introduction.”
In Japanese, if it’s clear that you are the one doing it, it’s enough to say:
- 明日の朝礼で短い自己紹介をします。

Adding 私は is not wrong, but often unnecessary:

（私は）明日の朝礼で短い自己紹介をします。

We usually include 私は / 僕は / 私たちは only when:

introducing a new topic,
making a contrast (e.g. “I will, but he won’t”),
or avoiding confusion about who the subject is.

How is 短い working here grammatically? Why is it before 自己紹介?

短い is an い-adjective meaning “short.”

In Japanese, adjectives come before the noun they modify:

短い手紙 = a short letter
大きい家 = a big house
寒い日 = a cold day

So:

短い自己紹介 = “short self-introduction”

This is a single noun phrase:

短い自己紹介をします。
= “I’ll do a short self-introduction.”

Compare:

短く自己紹介します。
Here 短く is the adverb form, meaning “I’ll introduce myself briefly.”

Both are correct, but:

短い自己紹介 focuses on the self-introduction itself being short.
短く自己紹介します focuses more on how you’ll introduce yourself (in a brief way).

Can I change the word order, like 短い自己紹介を明日の朝礼でします?

Yes. Japanese word order is relatively flexible as long as the verb comes at the end.

Both are natural:

明日の朝礼で短い自己紹介をします。
- Context (when/where) → then the action.
- Feels like setting the scene first: “At tomorrow’s morning assembly, I’ll do a short self-introduction.”
短い自己紹介を明日の朝礼でします。
- Puts a bit more emphasis on what you’ll do (the short self-introduction), then clarifies the setting.

Other orders like:

明日、朝礼で短い自己紹介をします。
朝礼で、明日短い自己紹介をします。 (less common but possible in the right context)

are also possible. The differences are mostly in subtle emphasis, not grammar.

What politeness level is します? Could I use する or いたします instead?

します is the standard polite form (ます-form). It’s appropriate in most school and workplace situations.

Plain / casual: する
- 明日の朝礼で短い自己紹介をする。
  → Casual, used with friends/peers.
Polite: します
- 明日の朝礼で短い自己紹介をします。
  → Neutral polite; fine to say to teachers, coworkers, etc.
Extra-polite / humble: いたします
- 明日の朝礼で短い自己紹介をいたします。
  → Very polite, humble. Good in formal business emails or when speaking to superiors or clients.

So you choose based on relationship and formality.

Is を necessary after 自己紹介, or can I say 自己紹介します?

Both are used:

自己紹介をします。
自己紹介します。

With so‑called サ変名詞 (verbal nouns) like:

勉強（する）
仕事（する）
経験（する）
自己紹介（する）

you can often either:

use the pattern [noun] + を + する, or
treat the whole as one verb [noun] + する.

So:

自己紹介をする and 自己紹介する both mean “to introduce oneself.”

In everyday speech, 自己紹介します (without を) is very common and completely natural. Including を is also correct; it can sometimes feel a bit more explicit/formal, but the difference is small.

Why use 短い instead of something like ちょっと? Can I say ちょっと自己紹介します?

You can use both, but the nuance is slightly different.

短い自己紹介をします。
- Directly describes the self-introduction as being short in length.
- Neutral, clear, slightly more formal/literal.
ちょっと自己紹介します。
- ちょっと literally = “a little / a bit.”
- Here it often functions like:
  “Let me just introduce myself real quick,”
  or “I’ll briefly introduce myself.”
- It’s a bit more casual / conversational.

You can also say:

ちょっとした自己紹介をします。
→ “I’ll do a little self-introduction.” (soft, modest tone)

In a formal school or company context, 短い自己紹介をします or simply 自己紹介します are very safe, neutral choices.

Why is it 明日の朝礼 instead of something like 明日に朝礼で?

Two points:

明日の朝礼 vs 明日朝礼で
- 明日の朝礼
  → “tomorrow’s morning assembly” (one noun phrase)
  → emphasizes that the assembly itself is the one taking place tomorrow.
- 明日朝礼で
  → “tomorrow, at the morning assembly, …”
  → 明日 functions as a time adverb (“tomorrow”), separate from 朝礼で.
You could say:
- 明日、朝礼で短い自己紹介をします。
  and it would be perfectly natural:
  “Tomorrow, at the morning assembly, I’ll do a short self-introduction.”
Why not 明日に?
For simple time expressions like 明日, 今日, 昨日, Japanese usually omits に:
- 明日行きます。= I’ll go tomorrow.
- 今日帰ります。= I’ll go home today.
明日に行きます is usually not used in this sense (it sounds odd or very marked).

So:

明日の朝礼で短い自己紹介をします。
→ perfectly natural and slightly more “packed” as a single phrase: “At tomorrow’s morning assembly…”
明日、朝礼で短い自己紹介をします。
→ also natural: “Tomorrow, at the morning assembly, I’ll do a short self-intro.”

Both are correct; the original just chooses the “tomorrow’s morning assembly” style.