asita no maturi ni ha, aoi yukata wo kite iku tumori desu.

In normal Japanese writing, there are usually no spaces between words. This sentence would normally be written as:

明日の祭りには、青い浴衣を着ていくつもりです。

Spaces are often added in textbooks or study materials to help learners see the parts more clearly.

A natural reading is:

あした の まつり には、あおい ゆかた を きて いく つもり です。

A few helpful readings:

• 明日 → あした
• 祭り → まつり
• 青い → あおい
• 浴衣 → ゆかた
• 着て → きて

Also, the particle は is pronounced わ, so には sounds like にわ.

の connects nouns and shows that one noun modifies another.

So:

• 明日 = tomorrow
• 祭り = festival
• 明日の祭り = tomorrow’s festival / the festival tomorrow

It works a lot like of or the English possessive ’s, though in Japanese it is much more widely used.

には is に + は.

• に marks the target, destination, or occasion
• は marks the topic, and sometimes adds a slight contrastive feeling

So 明日の祭りには means something like:

• as for tomorrow’s festival
• for tomorrow’s festival
• to tomorrow’s festival

In this sentence, it sets up the situation: regarding tomorrow’s festival, ...

Japanese often uses に with events when talking about going to them, participating in them, or doing something for them.

Examples:

• パーティーに行く = go to a party
• 会議に出る = attend a meeting
• 祭りに行く = go to a festival

Here, even though the verb is not directly 行く by itself, the sentence still treats the festival as the occasion/destination connected to the action.

This is one of the special pronunciation rules for Japanese particles.

When は is used as a topic particle, it is pronounced わ, not は.

So:

• は as a particle → wa
• には → niwa

But when は is part of a normal word, it is usually pronounced ha.

青い is an い-adjective, and い-adjectives can directly modify nouns.

So:

• 青い浴衣 = a blue yukata

This is the normal and natural way to say it.

青の浴衣 is not the usual basic phrasing here. You would normally use 青い when simply describing the color of the yukata.

着ていく is 着る in て-form plus いく.

• 着る = to wear / to put on
• 着ていく = to put it on and go / to go wearing it

So this does not just mean I will wear a yukata in a general sense. It specifically suggests:

• the speaker will put on the yukata
• then go to the festival wearing it

It emphasizes the idea of wearing it to that destination/event.

Yes, you could, and it would still be understandable.

But there is a nuance difference:

• 青い浴衣を着るつもりです = I intend to wear a blue yukata
• 青い浴衣を着ていくつもりです = I intend to go wearing a blue yukata

The version with 着ていく feels more connected to the trip to the festival itself.

つもりです expresses intention or plan.

So 着ていくつもりです means:

• I intend to go wearing it
• I’m planning to wear it and go

It sounds like a personal plan or decision.

They are similar, but not identical.

• つもりです = personal intention
• 予定です = scheduled plan / arrangement

So:

• 青い浴衣を着ていくつもりです = I intend to go wearing a blue yukata
• 青い浴衣を着ていく予定です = It is planned/scheduled that I will go wearing a blue yukata

つもりです feels more like the speaker’s own intention.
予定です can sound a little more fixed or arranged.

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

So even though 私は is not written, the sentence naturally implies something like:

• I
• or possibly we, depending on context

A full version could be:

私は明日の祭りには、青い浴衣を着ていくつもりです。

But in natural Japanese, leaving out the subject is very common.

The comma is helpful, but not strictly required.

It shows a pause after the topic:

明日の祭りには、青い浴衣を着ていくつもりです。

Without the comma, the sentence is still fine:

明日の祭りには青い浴衣を着ていくつもりです。

The comma just makes it a little easier to read and gives a natural pause.

Because here 明日 is directly modifying 祭り using の:

• 明日の祭り = tomorrow’s festival

So 明日 is part of a noun phrase, not acting by itself as a time expression for the whole sentence.

If the sentence were structured differently, you might see time words used in other ways, but here 明日 belongs together with 祭り.