daidokoro kara ii nioi ga site kite, karee no kaori da to sugu wakatta.

Here から means from or out of. It marks the starting point or source of the smell:

• 台所から = from the kitchen

So the sentence is saying that a nice smell was coming from the kitchen.

This is very natural with things like smells, sounds, light, voices, and wind:

• 部屋から音がする = A sound is coming from the room.
• 外からいい風が入ってくる = A nice breeze comes in from outside.

匂いがする is a very common expression meaning:

• to smell
• to give off a smell
• there is a smell

Literally, it is something like a smell does/is happening, but in natural English we just say it smells or I smell ... depending on context.

In Japanese, する is used in several sensory expressions:

• 音がする = a sound is heard / it makes a sound
• 味がする = it tastes like ...
• 気がする = I feel like ... / it seems to me ...

So いい匂いがしてきて means a nice smell started to come / I began to smell something nice.

The particle が marks いい匂い as the thing that is occurring or being perceived.

So:

• いい匂いがする = There is a nice smell / Something smells nice

You might wonder why not を. That is because する here is not acting like to do with a direct object. Instead, 匂いがする is a set expression where the smell is marked with が.

Compare:

• 音がする = There is a sound
• 変な感じがする = I have a strange feeling

してきて is the て-form of してくる, from する + くる.

In this sentence, 〜てくる shows that something comes into the speaker’s awareness or begins and reaches the speaker over time. With smells, sounds, feelings, and changes, this is very common.

So:

• 匂いがしてくる = a smell comes / starts to be noticeable
• 寒くなってくる = it starts getting cold
• 分かってくる = to gradually come to understand

Here いい匂いがしてきて suggests:

• a nice smell came drifting over, or
• the speaker began to notice a nice smell

It gives a stronger sense of development than just いい匂いがして.

Each form gives a different nuance:

• いい匂いがした = There was a nice smell / I smelled something nice
  This just states the fact.

• いい匂いがして = Smelling something nice, ...
  This links to the next part, but does not emphasize the smell coming toward the speaker.

• いい匂いがしてきて = A nice smell came over / started to be noticeable, and ...
  This adds the nuance that the smell reached the speaker or arose in the speaker’s awareness.

So してきて is chosen because it paints a more vivid scene.

They are similar, but the nuance is slightly different.

• 匂い is the general word for smell/odor
• 香り often sounds more pleasant, refined, or fragrance-like

So the sentence goes from:

• いい匂い = a nice smell

to

• カレーの香り = the aroma of curry

This sounds very natural. The first part is about sensing something pleasant without knowing exactly what it is yet. The second part identifies it more specifically as the aroma of curry.

Also, 匂い can sometimes be neutral or even negative depending on context, while 香り is usually positive.

カレーの香り literally means the aroma of curry.

The particle の connects two nouns. It can show many relationships, but here it means something like:

• aroma of curry
• curry aroma

So:

• カレー = curry
• 香り = aroma
• カレーの香り = the aroma/scent of curry

Other similar examples:

• コーヒーの香り = the aroma of coffee
• 花の香り = the scent of flowers

だと here marks the content of what was understood or realized.

So:

• カレーの香りだと分かった = I understood/realized that it was the smell of curry

This と works like that in English after verbs of saying, thinking, realizing, noticing, etc.

Because カレーの香り is a noun phrase, you use だ before と:

• 〜だと分かった = realized that it was ...

Compare:

• 先生だと分かった = I realized that he was a teacher.
• 静かだと分かった = I realized that it was quiet.

With い-adjectives and verbs, you do not use だ:

• おいしいと分かった
• 雨が降っていると分かった

Not here, if you keep カレーの香り as a noun phrase.

Because カレーの香り is a noun, standard Japanese uses:

• カレーの香りだと分かった

Without だ, it sounds ungrammatical in standard Japanese.

This is the same pattern as:

• 犯人だと分かった = I realized he was the culprit.
• 夢だと分かった = I realized it was a dream.

すぐ means immediately, right away, or quickly. It modifies 分かった:

• すぐ分かった = I understood right away / I immediately knew

Its position is very natural here. In Japanese, adverbs often come before the verb they modify.

So the flow is:

1. A nice smell came from the kitchen
2. The speaker immediately realized it was curry

In this sentence, realized or recognized is probably the best natural English choice.

分かる has a broad range of meanings, including:

• understand
• know
• realize
• recognize
• figure out

Here the speaker identifies the smell, so the nuance is:

• I immediately realized it was the smell of curry
• I knew right away it was curry

So while understood is not wrong, realized sounds more natural in English here.

The subject is omitted because Japanese often leaves out information that is obvious from context.

Here, the unstated subject is most naturally:

• I realized right away ...

So the full idea in English is something like:

• I immediately realized it was the smell of curry.

Japanese frequently omits I, you, he, she, etc. if the context makes them clear. This is one of the most common features English speakers have to get used to.

The て-form connects the first event to the second event:

• いい匂いがしてきて、カレーの香りだとすぐ分かった。

This means something like:

• A nice smell came from the kitchen, and I immediately realized it was curry.
• Smelling a nice aroma coming from the kitchen, I immediately knew it was curry.

The て-form can show:

• sequence
• cause/reason
• accompanying circumstances

Here it feels like a mix of sequence and cause: the smell came, and because of that, the speaker realized it was curry.

The comma just helps readability and shows a pause.

Usually no, not in this sentence.

• 臭い（くさい / におい） often suggests a bad smell or something unpleasant.
• 匂い is more neutral/general.
• 香り is pleasant and refined.

Since this sentence is talking about a pleasant curry smell, いい匂い and 香り are much more natural.

For example:

• 変な臭いがする = There’s a weird/bad smell.
• いい匂いがする = It smells nice.
• 花の香り = the scent of flowers.

Yes, that is possible.

• カレーの匂い = the smell of curry
• カレーの香り = the aroma of curry

The difference is mostly nuance:

• 匂い is more neutral and everyday
• 香り sounds a little more pleasant or elegant

Since curry is appetizing, 香り sounds especially nice, but 匂い would not be wrong.

It strongly suggests the speaker is personally perceiving the smell.

The combination of:

• 台所から
• いい匂いがしてきて
• すぐ分かった

creates the scene of the smell drifting from the kitchen to the speaker, who then recognizes it.

So it is not just an objective statement like there was a smell in the kitchen. It is more like:

• A nice smell came from the kitchen, and I immediately recognized it as curry.

That personal perception is part of why 〜てくる works so well here.