sekkaku hayaku okita noni, densya ga okurete simaimasita.

せっかく means something like after going to the trouble of..., especially, or since I made the effort to....

In this sentence, it adds the feeling that the speaker did something worthwhile or inconvenient — getting up early — but the result was disappointing.

So it gives the sentence an emotional nuance like:

• I got up early for nothing
• Even though I made the effort to get up early...

It often appears in situations where someone wants to say it was a shame that the effort did not pay off.

早い is the dictionary form of the adjective early.
When an い-adjective modifies a verb, it changes to its -く form.

So:

• 早い = early
• 早く起きる = to get up early

Here, 早く modifies 起きた because it describes how the person got up.

Compare:

• 早い電車 = an early train
• 早く起きた = got up early

Because the speaker is referring to the completed action got up early.

The structure is:

• 早く起きた = got up early
• 早く起きたのに = even though I got up early...

Before のに, Japanese often uses a plain clause, and that clause can be in present or past depending on the meaning.

Examples:

• 行くのに = even though I go / will go
• 行ったのに = even though I went

So 起きた is simply past tense because the action happened before the train delay.

Here, のに means even though, although, or despite the fact that.

It connects two ideas where the second part goes against what you would normally expect from the first part.

In this sentence:

• せっかく早く起きたのに = even though I went to the trouble of getting up early
• 電車が遅れてしまいました = the train ended up being delayed

The implied expectation is:

• If I get up early, things should go smoothly.

But that expectation is broken, so のに expresses disappointment or frustration.

が marks 電車 as the subject of 遅れる.

• 電車が遅れる = the train is delayed / the train runs late

The verb 遅れる describes what happens to the train, so 電車 is the thing that undergoes that state.

A learner may wonder whether は could be used instead. It could, depending on context:

• 電車が遅れた = the train was delayed
• 電車は遅れた = as for the train, it was delayed

In this sentence, が is the most neutral and natural choice for introducing the event.

遅れて is the て-form of 遅れる.

• dictionary form: 遅れる
• て-form: 遅れて
• past polite with しまう: 遅れてしまいました

The て-form here connects 遅れる to しまいました.

So the grammar is:

• 遅れる
  • てしまう
• 遅れてしまう
• past polite: 遅れてしまいました

This creates the meaning ended up being delayed or unfortunately was delayed.

〜てしまいました comes from 〜てしまう, which often adds one of these nuances:

1. completion — something finished completely
2. regret / disappointment / unfortunate result

In this sentence, the important nuance is unfortunate result.

So:

• 電車が遅れました = the train was delayed
• 電車が遅れてしまいました = the train ended up being delayed / unfortunately, the train was delayed

Because the first half already sets up disappointment with せっかく and のに, しまいました fits very naturally.

Yes. You could say:

• せっかく早く起きたのに、電車が遅れました。

This still means Even though I got up early, the train was delayed.

However, 遅れてしまいました sounds a little more emotional and a little more natural in this context because it emphasizes that the delay was an unfortunate outcome.

So:

• 遅れました = neutral fact
• 遅れてしまいました = unfortunate or disappointing fact

Not exactly, but it often carries a sense of contrast, and very often that contrast feels disappointing, surprising, or contrary to expectation.

In this sentence, it is definitely used in a disappointing way.

A simple way to think about it is:

• A のに B = even though A, B happened anyway

Often B is something the speaker did not want or did not expect.

That is why のに is very common in complaints, regrets, and emotional reactions.

The subject is understood from context: it is most naturally I.

So the full idea is:

• I got up early, but the train was delayed.

Japanese often leaves out subjects when they are obvious from context. Since this sounds like a personal complaint or report, listeners naturally understand that the speaker is talking about themselves.

This omission is very normal in Japanese and much more common than in English.

The comma separates the contrasting clauses:

• せっかく早く起きたのに、
• 電車が遅れてしまいました。

This makes the sentence easier to read and highlights the emotional contrast:

1. the speaker made an effort
2. the result was still bad

In Japanese, punctuation is somewhat flexible, but this comma is very natural because のに sets up a strong contrast and the pause helps the sentence flow clearly.