itizikan entyousite, motikomi ga dekiru kositu de moriagatta.

Here 一時間 means by one hour / for an additional hour in the sense of extending the reservation.

So 一時間延長して means we extended it by one hour.

A learner might first think it means for one hour we got excited, but in this sentence 一時間 goes with 延長して, not with 盛り上がった.

延長して is the て-form of 延長する, meaning to extend.

The て-form here connects actions:

• 一時間延長して = after extending it by one hour / and extending it by one hour
• 盛り上がった = we got lively / had a great time

So the sentence describes a sequence of events:

1. the time was extended,
2. then people had a great time in the room.

Depending on context, the て-form can sound like:

• and
• after doing
• by doing

Here and/after extending is the most natural reading.

Both can express possibility, but they work a little differently.

• 持ち込める = the potential form of 持ち込む, meaning can bring in
• 持ち込みができる = literally bringing-in is possible

In signs, ads, store descriptions, and venue descriptions, Noun + ができる is very common and sounds natural:

• 駐車ができる = parking is possible
• 利用ができる = use is possible
• 持ち込みができる = bringing your own items is allowed/possible

So 持ち込みができる個室 means a private room where bringing your own food/drinks is allowed. It has a slightly descriptive, facility-related feel.

In this pattern, が marks the thing that is possible.

So:

• 持ち込みができる = bringing things in is possible
• literally, as for bringing things in, that can be done

This is different from marking a direct object with を. Since できる often takes が for what is possible, 持ち込みができる is the natural structure here.

持ち込み is a noun form from 持ち込む.

It usually means bringing something in, and in real-life situations it often refers to:

• bringing your own drinks
• bringing your own food
• bringing outside items into a venue

So in a sentence like this, 持ち込みができる usually means you are allowed to bring your own food or drinks into the room.

This is a very common Japanese structure: a clause comes before a noun and directly modifies it.

So:

• 持ち込みができる = where bringing your own items is allowed
• 個室 = private room

Together:

• 持ち込みができる個室 = a private room where you can bring your own food/drinks

Japanese does not need a relative pronoun like that, which, or where here. The modifying clause simply goes before the noun.

で marks the place where an action happens.

So:

• 個室で盛り上がった = we got lively / had a great time in the private room

It is not marking destination or location of existence. It marks the setting of the action.

Compare:

• 個室で話す = talk in a private room
• 個室に入る = enter a private room
• 個室にいる = be in a private room

Here, since 盛り上がる is an action/event, で is the correct particle.

Literally, 盛り上がる can mean something like rise up or swell, but in conversation it often means:

• to get excited
• to become lively
• to have a great time
• to really get going

So in this sentence, 盛り上がった means the atmosphere became fun and energetic. It is often used for parties, conversations, karaoke, gatherings, and events.

Natural translations include:

• We had a great time
• Things got really lively
• We got really into it

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

From context, it probably means:

• we had a great time
• the group got lively
• everyone got excited

Japanese often leaves out subjects and topics when they are understood from context. So the sentence does not need to explicitly say we.

It is about the people extending their time, not the room itself changing.

一時間延長して refers to extending the booking/reservation/use time by one hour.

So the idea is:

• they were using a private room,
• they extended the session by one hour,
• and they had a great time there.

In natural usage, 一時間延長する normally means extend it by one hour.

If you wanted to say something more like continued for one extra hour, Japanese would usually express that differently depending on the situation.

So the most natural understanding here is:

• we extended the reservation by one hour

not

• we spent one hour extending something

The comma is not grammatically required, but it helps readability.

It shows a pause between:

• 一時間延長して
• 持ち込みができる個室で盛り上がった

Without the comma, the meaning is basically the same:

• 一時間延長して持ち込みができる個室で盛り上がった

Writers often use commas in Japanese to make long phrases easier to read.

No. In normal Japanese, this would usually be written without spaces:

一時間延長して、持ち込みができる個室で盛り上がった。

Spaces are often added in learning materials to make the sentence easier to parse. They are not normally used this way in everyday Japanese writing.

A helpful chunk-by-chunk breakdown is:

• 一時間延長して = extending it by one hour
• 持ち込みができる個室で = in a private room where bringing your own food/drinks was allowed
• 盛り上がった = we had a great time / things got lively

So the whole sentence is describing a fun time in a private room, with the extra detail that:

• the time was extended by one hour, and
• outside food/drinks were allowed.