Learn Hardcore Japanese: ryokougaisya no hito ha totemo sinsetu de, soudanaite tosite ansin dekimasu. - The person at the travel agency was very kind and is someone I can feel at ease talking with.

In 旅行会社の人, it most naturally means “the staff / the people who work at the travel agency”, i.e. a general group rather than one specific person.

Why?

There is no specific person mentioned before.
The sentence talks about a general quality (とても親切 “very kind”), which fits talking about the staff as a whole.

If you wanted to make the plurality explicit, you could say:

旅行会社の人たち – clearly “the people (plural) at the travel agency,” but even without たち, native speakers usually understand this as plural here.

Why is の used between 旅行会社 and 人? Is it possession?

の has several functions; one of them is to link a describing noun to another noun, similar to “of” or an apostrophe-s in English.

旅行会社の人 literally is:

旅行会社 – travel agency
の – “of / belonging to / related to”
人 – person / people

So it means “person/people of the travel agency”, which in natural English is “the people at the travel agency” or “the travel agency staff.”

It’s not only strict ownership; の here indicates a relationship/affiliation:

会社の人 – people of the company (employees)
銀行の人 – people at the bank (bank staff)
学校の先生 – teacher of the school (teacher there)

Why is は used after 人 instead of が?

は marks the topic, and が typically marks the grammatical subject or emphasizes “who/what does X.”

In 旅行会社の人はとても親切で…:

旅行会社の人は introduces “the people at the travel agency” as the topic: “As for the people at the travel agency…”
The real focus of the sentence is the comment about them: they are kind, and you can feel at ease consulting them.

If you used が instead (旅行会社の人がとても親切で…), it would sound like:

“It is the people at the travel agency who are very kind (as opposed to someone else).”

So は is more neutral and typical when you are describing a general characteristic of something.

What does 親切で mean exactly, and what is で doing here?

親切 is a na-adjective meaning “kind” / “helpful.”
The form 親切で is its te-form, used to connect it to the next part of the sentence.

For na-adjectives, the te-form is made with で:

親切だ → 親切で
便利だ → 便利で
有名だ → 有名で

In this sentence:

とても親切で、相談相手として安心できます。
means:
“(They) are very kind and, as someone to consult, (you) can feel at ease.”

So で here is not the usual particle meaning “at” or “by means of.”
It is the conjunctive/te-form of the na-adjective 親切 used to link two descriptions:

They are very kind
You can feel at ease relying on them as someone to consult

Could I say とても親切です instead of とても親切で? What would change?

Yes, but you’d need to change the sentence structure.

とても親切で、相談相手として安心できます。
= “(They) are very kind, and (you) can feel at ease consulting them.”
One sentence with 親切で linking to the second part.

If you use です, it ends the sentence:

旅行会社の人はとても親切です。相談相手として安心できます。
= “The people at the travel agency are very kind. You can feel at ease consulting them.”

So:

親切で → one sentence, smoother connection, “and…”
親切です。 → two separate sentences, a bit more segmented.

Both are correct; the original is just more naturally connected.

What exactly does 相談相手 mean? How is it formed?

相談相手 is a compound noun:

相談 – consultation; to consult (as a noun/verb stem)
相手 – partner, counterpart, the person on the other side of some interaction

Put together:

相談相手 = “someone you talk to / consult with”, i.e. “a person to discuss things with or get advice from.”

So 相談相手として means “as someone to consult” / “as a person to talk to for advice.”

It’s a commonly used word:

友達は何でも話せる相談相手です。
– “My friend is someone I can talk to about anything.”

What is the function of として in 相談相手として?

として means “as / in the role of / in the capacity of.”

Pattern:

Noun + として + action / evaluation
→ “do / be something as Noun”

So:

相談相手として安心できます
= “(They are) reassuring as a person to consult,” or
= “You can feel at ease having them as someone to consult.”

Other examples of として:

先生として働いています。
– “I work as a teacher.”
友人として言いますが、それはよくないと思います。
– “I say this as a friend, but I think that’s not good.”

Why is it 安心できます and not 安心です or 安心します?

The key is できます, which expresses “can / be able to.”

安心する – to feel safe / at ease; to feel reassured
安心できる – can feel safe / be able to feel at ease
安心できます – polite form of 安心できる

So:

安心できます = “(I/you) can feel at ease / can feel reassured.”

If you said:

安心です – “(It) is safe / (I am) relieved” – just a state, no “can.”
安心します – “(I) feel relieved / will feel at ease” – action, but no sense of “ability.”

The original sentence wants to say:

“They are very kind, and you can feel at ease with them as someone to consult.”
That “can” idea is why Japanese uses できます (potential) rather than just です or します.

What is the underlying structure behind 安心できます? Is there a missing する?

You can think of it as a shortened form of:

安心することができます。

Breakdown:

安心する – to feel at ease
〜ことができる – can do 〜

In everyday Japanese, for suru-verbs (like 勉強する, 相談する, 安心する), the pattern often simplifies:

安心する → 安心できる
勉強する → 勉強できる
相談する → 相談できる

So 安心できる / 安心できます is essentially “can安心する”.
The する is not really “missing”; it’s built into this standard pattern of potential form for 〜する verbs.

Is 安心 a noun, an adjective, or a verb?

安心 is one of those Japanese words that can function in multiple ways:

As a noun:
- 安心 – peace of mind, relief
- 安心が大切です。 – “Peace of mind is important.”
As a na-adjective:
- 安心な町 – a safe town
- 安心な場所 – a place where you can feel at ease
As part of a suru-verb:
- 安心する – to feel relieved / at ease

In 安心できます, it’s coming from the verb 安心する, in its potential form:

安心する → 安心できる / 安心できます

Can I reorder it like とても親切で、安心できます、相談相手として?

No, that word order would be unnatural and confusing in Japanese.

The usual pattern is:

[Role] + として + [verb / evaluation]

So you want:

相談相手として安心できます
not
安心できます相談相手として

The original word order:

…とても親切で、相談相手として安心できます。
is natural and standard:
“(They) are very kind, and (you) can feel at ease with them as someone to consult.”

Could I say 旅行会社の人たちは instead of 旅行会社の人は? What would change?

Yes, 旅行会社の人たちは is grammatically correct.

人 – person / people (number left vague)
人たち – explicitly “people” or “a group of people”

旅行会社の人は

Usually already understood as “the staff / the people at the travel agency.”

旅行会社の人たちは

Emphasizes that you’re clearly talking about multiple people, a group.

In this context, both are fine. 人 alone is more common and natural; 人たち adds a bit of explicit plurality, sometimes a slightly more personal or “group” feeling, but the meaning here doesn’t change much.

What is the politeness level of this sentence? Is it formal or casual?

The sentence is in polite form, suitable for most everyday situations:

親切で – neutral/conjunctive
安心できます – ます-form (polite)

This level is appropriate for:

Talking to acquaintances
Writing a review
Giving a recommendation
Any normal conversation where polite Japanese is expected

It’s not super-formal (like adding 敬語 everywhere), but it is good standard polite Japanese.

How would this sentence change in casual speech?

A common casual version would be:

旅行会社の人はとても親切で、相談相手として安心できる。

Changes:

安心できます → 安心できる (plain form; no ます)

If you were speaking very casually to a close friend, you might also drop とても or add some softeners:

旅行会社の人、すごく親切で、相談相手として安心できるよ。

But the basic grammar (親切で, 相談相手として, 安心できる) stays the same.