haha ha, nori wo komakaku kitte, udon ni iremasita.

は marks 母 as the topic of the sentence: as for mother, this is what she did.

In this sentence, the speaker is not mainly identifying who did the action; they are telling what the already-known topic, mother, did. So 母は sounds very natural.

If you used 母が, it would put more focus on mother as the one who did it, often with a nuance like it was mother who... or in a context where the subject is being newly introduced or contrasted.

So here:

• 母は = speaking about mother as the topic
• 母が = focusing on mother as the subject

を marks the direct object of the verb.

Here, the thing being cut is 海苔, so:

• 海苔を切って = cut the seaweed

Even though the sentence later continues to another verb, 海苔 is still the object of 切って.

細かい is an i-adjective meaning something like small/fine/minute.

To modify a verb, an i-adjective usually changes to its adverbial form, which ends in -く:

• 細かい → 細かく

So:

• 細かく切る = cut finely / cut into small pieces

This is similar to how English uses an adverb in cut finely.

切って is the te-form of 切る.

In this sentence, the te-form is used to link actions:

• 海苔を細かく切って、うどんに入れました
• cut the seaweed finely, and put it into the udon

A very common use of the te-form is to connect one action to the next. Here it shows that the cutting happened before the putting in.

Yes. That is the normal reading.

With the te-form, the sequence is usually understood as:

1. 海苔を細かく切って = she finely cut the seaweed
2. うどんに入れました = then she put it into the udon

So the order of actions matters here.

Because に marks the destination/location something is put into.

Here, the thing being put in is the seaweed, and the place it goes is the udon:

• うどんに入れました = put it into the udon

If you said うどんを入れました, then udon would be the direct object, meaning put in the udon somewhere else. That would describe a different situation.

So in this sentence:

• implied object: the seaweed
• destination: うどんに

Japanese often omits words that are already clear from context.

In this sentence, after 海苔を細かく切って, it is easy to understand that the thing she then put into the udon was the seaweed. So Japanese does not need to repeat it.

A fuller version could be something like:

• 母は海苔を細かく切って、それをうどんに入れました。

But that sounds more explicit than necessary in ordinary speech.

入れました is the polite past form of 入れる, which means to put in or to insert.

Breakdown:

• 入れる = dictionary form
• 入れます = polite non-past
• 入れました = polite past

So 入れました means put in / added in a polite style.

In a sentence like this, 母 usually means my mother or the speaker’s mother, depending on context.

Japanese often uses family terms without saying my when the relationship is understood. So 母は naturally means my mother if the speaker is talking about their own family.

If the speaker wanted to say someone else’s mother, the sentence would usually make that clearer from context or wording.

The commas are mainly there to make the sentence easier to read and to show pauses:

• 母は、海苔を細かく切って、うどんに入れました。

Japanese commas are often more flexible than English commas. They can mark natural pauses or help separate chunks of information, but they are not always strictly required.

So the sentence would still be grammatical without them:

• 母は海苔を細かく切ってうどんに入れました。

The commas just improve readability.

To some extent, yes. Japanese word order is more flexible than English, as long as the particles make the roles clear.

For example, these are still understandable:

• 母はうどんに海苔を細かく切って入れました。
• 海苔を細かく切って、母はうどんに入れました。

However, the original order is very natural and easy to process:

• 母は、海苔を細かく切って、うどんに入れました。

So while word order can vary, some versions sound smoother or more standard than others.