kubiwa ga sukosi ookikatta node, ie ni kaette kara naosimasita.

Because 大きかった is the past form of the i-adjective 大きい.

• 大きい = is big
• 大きかった = was big

In this sentence, the speaker is talking about the collar being too big at the time they noticed it and then fixed it, so the past form is natural.

ので means because or since. It connects the reason to the result.

So:

• 首輪が少し大きかったので = Because the collar was a little big
• 家に帰ってから直しました = I fixed it after going home

Compared with から, ので often sounds a bit softer and more explanatory.

が marks 首輪 as the thing being described by 大きかった.

So:

• 首輪が少し大きかった = The collar was a little big

This is a very common pattern:

• Noun + が + adjective

Examples:

• 部屋が寒い = The room is cold
• サイズが小さい = The size is small

Here, 首輪 is the thing that had the property of being too big.

少し means a little or slightly.

So 少し大きかった means:

• was a little big
• was slightly too big

It softens the statement. The collar was not extremely large, just somewhat too large.

家に帰ってから means after returning home.

It is made of:

• 家に = to home
• 帰って = te-form of 帰る (to return/go back)
• から = after

Pattern:

• Verb-te form + から = after doing X

So:

• 帰ってから直しました = I fixed it after going home

This shows the order of actions:

1. went home
2. fixed it

The particle に marks the destination of 帰る.

• 家に帰る = return home
• 学校に行く = go to school

With motion verbs, に often marks the place you go to.

You may also sometimes see 家へ帰る. That is also possible, but 家に帰る is very common.

直しました is the polite past form of 直す, which means to fix, to correct, or to adjust/repair depending on context.

In this sentence, it probably means something like:

• adjusted it
• fixed it
• altered it so it fit better

Since the collar was a little too big, 直しました likely means the speaker modified it in some way.

Not always. 直す is broader than just repair.

Depending on context, it can mean:

• repair something broken
• correct a mistake
• adjust something that is not right

Here, because the collar was too big, 直しました probably means adjusted it/fixed the size, not necessarily that it was broken.

Japanese often leaves out the subject when it is clear from context.

So 直しました does not explicitly say I fixed it, but that is the most natural interpretation in many contexts.

A fuller version could be:

• 私は、首輪が少し大きかったので、家に帰ってから直しました。

But Japanese usually omits 私は if it is already understood.

The object is omitted because it is obvious from context: it is the collar.

A more explicit version would be:

• 首輪が少し大きかったので、家に帰ってからそれを直しました。
• 首輪が少し大きかったので、家に帰ってから首輪を直しました。

But Japanese often omits things that are already understood, especially objects and subjects.

Yes, it could:

• 首輪が少し大きかったから、家に帰ってから直しました。

This also means Because the collar was a little big, I fixed it after going home.

The difference is mainly nuance:

• ので = a bit softer, more explanatory, often more neutral/polite
• から = more direct, more conversational in many cases

Both are grammatical here.

Because 帰ってから clearly means after going home.

Compare:

• 帰ってから直しました = I fixed it after going home
• 帰って直しました = I went home and fixed it / I returned and fixed it

The version with から emphasizes the sequence more explicitly.

Usually 家 here means home, not just the physical building.

So 家に帰る is commonly translated as:

• go home
• return home

Even though 家 literally means house/home, in everyday Japanese this expression often has the natural English meaning go home.

Because the sentence does not need an explicit topic. Japanese often omits the topic when it is already known.

If you wanted to set up a topic, you could say:

• 首輪は少し大きかったので、家に帰ってから直しました。

This would make the collar the topic.

But the original uses 首輪が, which focuses on the collar as the thing that was a little big. That sounds very natural.

首輪 means collar, usually an animal collar, such as a dog or cat collar.

It is made of:

• 首 = neck
• 輪 = ring

So literally it is something like a neck ring, though in normal English you should just think collar.

No. Normal Japanese writing usually does not use spaces between words.

So this sentence would normally be written like this:

首輪が少し大きかったので、家に帰ってから直しました。

The spaces are probably included only to make it easier for learners to see the parts of the sentence.

Yes. It is in polite style because of 直しました.

• dictionary/plain form: 直した
• polite form: 直しました

The rest of the sentence does not need special polite marking, so the sentence sounds natural and polite overall.