tennyuubi ha asita desu.

A common reading is:

てんにゅうび は あした です。

A few notes:

• 転入日 = てんにゅうび
• 明日 is most commonly あした in everyday speech
• In more formal speech, 明日 can also be read あす
• Very formal or written-style みょうにち is also possible in some contexts, but less likely in ordinary conversation

So in normal spoken Japanese, てんにゅうびはあしたです is the safest reading.

転入日 means the date of transfer/moving in, but the exact nuance depends on context.

For example, it can refer to:

• the date someone transfers into a new school
• the date someone officially moves into a new city or ward
• the official date of entering a new institution or area

This word is fairly formal and administrative. It is not just a casual moving day in every situation.

It is made of:

• 転入 = transfer in / move into
• 日 = day / date

So 転入日 is literally transfer-in date.

Japanese often leaves out information that is understood from context.

So 転入日 could mean:

• the transfer-in date
• your transfer-in date
• my transfer-in date
• our transfer-in date

depending on the situation.

Japanese also does not use articles like a or the the way English does. Instead, context tells you what is meant.

So if this appears on a form or in a conversation about your registration, 転入日は明日です。 would naturally be understood as something like Your transfer-in date is tomorrow or The transfer-in date is tomorrow.

は marks the topic of the sentence.

So:

• 転入日 = transfer-in date
• は = as for / speaking of
• 明日です = is tomorrow

A very natural way to understand the structure is:

As for the transfer-in date, it is tomorrow.

This does not always match English word-for-word. In English, we usually just say The transfer-in date is tomorrow, but Japanese often organizes sentences as topic + comment.

It is best to think of 転入日 as the topic first.

In many simple sentences like this, the topic and the subject feel very similar, so translating it as the subject in English is fine. But grammatically, Japanese is using は, which marks the topic, not necessarily the subject in the same way English does.

So for learning purposes:

• English-style understanding: The transfer-in date is the subject
• Japanese-style understanding: As for the transfer-in date is the topic

Both ways can help, but the Japanese explanation is more accurate.

Here, 明日 is the predicate noun before です.

The sentence is an A is B type sentence:

• 転入日 = A
• 明日 = B
• です = is

So 明日 does not need a particle here.

It is not functioning like on tomorrow or at tomorrow. It is simply the thing being identified:

The transfer-in date is tomorrow.

Also, time words in Japanese often do not need particles anyway, but in this sentence the main reason is that 明日 is part of the X is Y pattern.

です is the polite copula. In a sentence like this, it works like is in English.

So:

• 転入日は明日です。 = The transfer-in date is tomorrow.

It makes the sentence polite and complete.

In casual speech, you could drop it:

• 転入日は明日。

But that sounds blunt or note-like, and it would not be the normal choice in polite conversation.

Usually, は is the most natural choice in a plain statement like this.

• 転入日は明日です。 = neutral, standard statement

If you say:

• 転入日が明日です。

it is not necessarily impossible, but it changes the nuance. It may sound like you are identifying which thing/date is tomorrow, or answering a question with special focus.

For example, it could make sense in a contrastive situation, but as a simple standalone statement, は is more natural.

So for learners, the safe default here is:

転入日は明日です。

Yes, it is natural, especially in formal or administrative contexts.

You might see or hear it in situations involving:

• city office registration
• school transfer paperwork
• company HR procedures
• housing or institutional forms

That said, 転入 is a somewhat formal word. In everyday casual conversation, if someone is just talking about moving house, they might say something more conversational, such as:

• 引っ越しは明日です。 = The move is tomorrow.
• 引っ越すのは明日です。 = I’m moving tomorrow.

So 転入日は明日です。 sounds natural, but it feels more official than casual.

Those spaces are usually just for learners.

Normal Japanese writing would be:

転入日は明日です。

Japanese does not normally use spaces between words the way English does. Textbooks, flashcards, and beginner materials sometimes add spaces to make sentence structure easier to see.