butyou to watasi no iken ga ittisimasita.

A natural way to parse it is:

• 部長と私の意見 = the manager's and my opinions
• が = subject marker
• 一致しました = matched / came into agreement

So the basic structure is:

[The manager's and my opinions] + [matched].

A more literal grammar view is [部長と私]の意見, where 部長と私 means the manager and I, and の links that whole group to 意見.

Here と connects two nouns and means and.

So:

• 部長と私 = the manager and I

This is one of the most common uses of と.

Be careful: と can also mean with, depending on the sentence, but in this sentence it is simply joining two nouns.

Because Japanese can attach の to the whole combined phrase:

• [部長と私]の意見

This means the opinions of the manager and me.

So 部長と私の意見 is a compact way to say:

• 部長の意見と私の意見

Both are possible, but they feel slightly different:

• 部長と私の意見 = more compact and smooth
• 部長の意見と私の意見 = more explicit, sometimes clearer or more emphatic

In Japanese, nouns usually do not show singular vs. plural the way English nouns do.

So 意見 can mean:

• opinion
• opinions

In this sentence, the meaning is naturally opinions, because we are talking about the manager's opinion and my opinion together.

That is why English normally translates it with a plural noun.

が marks the subject of 一致しました.

So the sentence presents 部長と私の意見 as the thing that matched.

Using は is also possible:

• 部長と私の意見は一致しました。

That version sounds more like:

• As for the manager's and my opinions, they matched.

Very roughly:

• が = presents the subject as the main piece of information
• は = marks it as the topic

In a standalone sentence, が is perfectly natural.

一致しました is the polite past form of 一致する.

• 一致 = agreement / coincidence / match
• する = to do
• 一致する = to agree / to match / to coincide
• 一致しました = agreed / matched / came into agreement

This is a fairly formal or objective expression. It is very common in business, writing, and formal speech.

It sounds a bit more formal than very casual alternatives.

Yes, absolutely.

• 部長と私は意見が一致しました。

This means something like:

• As for the manager and me, our opinions matched.

The difference is in focus:

• 部長と私の意見が一致しました focuses on the opinions
• 部長と私は意見が一致しました makes the manager and I the topic first

Both are natural, but the original sentence is a little more objective and compact.

Because Japanese often expresses this idea as opinions matched rather than directly saying we agreed.

So this sentence is not just about two people being in harmony in a vague sense. It specifically says that their views/opinions were the same.

That gives it a slightly more precise and formal feel.

Compare:

• 部長と私の意見が一致しました。
  The manager's and my opinions matched.

• 部長と私は同意しました。
  The manager and I agreed.

The first one often sounds more natural in formal contexts.

It is a title.

部長 usually means something like:

• department head
• general manager
• manager

The exact English job title depends on the company.

In Japanese, titles like 部長, 課長, 社長, and so on are often used by themselves, almost like names. Japanese also does not use articles like a or the, so 部長 by itself is completely normal.

Yes, that is grammatical.

• 私と部長の意見が一致しました。

It means the same thing.

However, in Japanese, especially in polite or business-like speech, it is often more natural to mention the other person before yourself:

• 部長と私 rather than 私と部長

So the original order sounds socially smoother in many situations.