kono aoi syatu ni suru ka, siroi syatu ni suru ka mayotte imasu.

In this sentence, N にする is a very common pattern meaning to choose N, to go with N, or to decide on N.

So:

• 青いシャツにする = choose the blue shirt / go with the blue shirt
• 白いシャツにする = choose the white shirt / go with the white shirt

This is different from the basic する meaning to do.

A useful way to remember it is:

• A をする often means do A
• A にする often means make it A / choose A

For example:

• コーヒーにします。 = I’ll have coffee.
• これにします。 = I’ll take this one.

So in your sentence, the speaker is wavering between two choices.

Here, か is marking alternatives: whether to choose the blue shirt or whether to choose the white shirt.

The pattern is:

• A か、B か ...
• whether A or B ...
• A or B ...

So:

• 青いシャツにするか、白いシャツにするか迷っています
• I’m wondering whether to choose the blue shirt or the white shirt

This is not exactly the same as the か used in simple questions like:

• 行きますか。 = Are you going?

Here, か is being used inside the sentence to present two possibilities.

Because each full option is being presented as a separate possibility.

The sentence is structured like this:

• 青いシャツにするか
• 白いシャツにするか
• 迷っています

Literally, it is close to:

• I am hesitating over whether to make it the blue shirt, or whether to make it the white shirt.

Japanese often repeats the full grammatical pattern in each option. In English, we might shorten it:

• I’m torn between the blue shirt and the white shirt.

But Japanese commonly keeps both clauses complete.

迷う means to be puzzled, to hesitate, to be unsure, or to be torn.

The -ている form in 迷っています shows an ongoing state. So the speaker is not just hesitating at one single moment; they are currently in a state of indecision.

• 迷う = to hesitate / be unsure
• 迷っている = am hesitating / am undecided / am torn

So:

• 迷っています = I’m hesitating / I’m torn / I’m undecided

This use of -ている is very natural because indecision is a continuing state.

That に is part of the fixed pattern N にする.

It does not mean to in the usual English sense. Instead, it marks the thing you are choosing or deciding on.

So:

• 青いシャツにする = choose the blue shirt
• 白いシャツにする = choose the white shirt

You should learn にする as a chunk when it has this meaning.

A very common example:

• どちらにしますか。 = Which one will you choose?
• こちらにします。 = I’ll choose this one.

この means this and modifies the noun directly:

• この青いシャツ = this blue shirt

So the speaker is not talking about blue shirts in general, but a specific blue shirt nearby or already identified in the situation.

Without この, it would simply be:

• 青いシャツにするか、白いシャツにするか迷っています。
• I’m undecided whether to choose a/the blue shirt or a/the white shirt.

Using この makes the blue shirt more specific.

Japanese often omits repeated information when it is obvious.

So even though only the first option explicitly says この, the second option may still be understood in context as the corresponding white shirt under consideration.

In other words, this can feel like:

• this blue shirt or the white shirt

If the speaker wanted to be fully parallel and explicit, they could say:

• この青いシャツにするか、この白いシャツにするか迷っています。

But that sounds more repetitive. Japanese often prefers the shorter version when the meaning is clear.

青い and 白い are i-adjectives, and they directly modify the noun:

• 青いシャツ = blue shirt
• 白いシャツ = white shirt

This is the most straightforward and natural way to say it.

While expressions with の can exist in some cases, colors like 青い and 白い are normally used as adjectives before nouns.

So a learner should get comfortable with:

• 赤い車 = red car
• 黒い猫 = black cat
• 白いシャツ = white shirt

No, it is not grammatically necessary, but it is often used in writing to make the sentence easier to read.

So both are possible:

• この青いシャツにするか、白いシャツにするか迷っています。
• この青いシャツにするか白いシャツにするか迷っています。

The comma just helps show the pause between the two alternatives.

The subject is omitted, which is very common in Japanese.

From context, the natural understanding is usually:

• 私は / 僕は / 俺は omitted
• I’m hesitating...

So the full idea is something like:

• (私は) この青いシャツにするか、白いシャツにするか迷っています。

Japanese leaves out subjects when they are already obvious from context. This is one of the most common features that English speakers have to get used to.

Yes, that is a very natural translation.

Because 迷っています can express indecision, good English translations include:

• I’m hesitating between this blue shirt and the white shirt.
• I’m not sure whether to choose this blue shirt or the white shirt.
• I’m wondering whether to go with this blue shirt or the white shirt.
• I’m torn between this blue shirt and the white shirt.

These all capture the same basic idea, even if the wording differs.

Yes. 迷っています usually suggests real indecision or difficulty choosing, not just casual thought.

Compare:

• 考えています = I’m thinking about it
• 迷っています = I’m unsure / I’m torn / I’m hesitating

So in this sentence, the speaker is not merely considering the options; they are having trouble deciding between them.

Yes, you can, and it is natural in many contexts.

• 青いシャツか、白いシャツか迷っています。

This means something like:

• I’m undecided between the blue shirt and the white shirt.

Adding にする makes the act of choosing more explicit:

• 青いシャツにするか、白いシャツにするか迷っています。
• I’m undecided about whether to choose the blue shirt or the white shirt.

So both are possible, but the version with にする emphasizes the decision more clearly.