Learn Hardcore Japanese: yuube ha zangyou no ato, senpai ga sasiire no keeki wo motte kite kurete, totemo uresikatta desu. - Last night, after working overtime, my senior brought cake as a treat, and I was very happy.

If you said 昨夜が…, it would sound like “last night (as opposed to other nights) was the one that…”, putting contrast or focus on “last night” as a subject. That’s not what we need here; we just want to set the scene in time.

So:

昨夜は残業のあと、先輩が…
“Last night, after overtime, my senpai…”

Time expressions are very commonly followed by は to set the context:

昨日は忙しかったです。 – As for yesterday, I was busy.
来週は休みです。 – As for next week, I’m off.

Why is it 残業のあと and not something like 残業してあと?

There are two main patterns with あと (“after”):

Noun + の + あと
- 残業のあと = “after overtime (work)”
  Here, 残業 is a noun, so it connects to あと with の.
Verb (plain past) + あと
- 残業したあと = “after (I) did overtime”
- 仕事が終わったあと = “after work finished”

Both 残業のあと and 残業したあと are grammatically fine.
Nuance:

残業のあと feels like you’re treating “overtime” as a block/time period on the schedule.
残業したあと slightly emphasizes the action of having done overtime.

Another very common alternative is:

残業してから = “after doing overtime / once overtime was done”

So you could also say:

昨夜は残業してから、先輩がケーキを持って来てくれて…

What exactly does 差し入れ mean? Is it just “present” or “gift”?

差し入れ is more specific than a general “present”.

It usually means:

Food or drinks (or small items) that you bring to people who are working hard (at the office, during a club activity, in a hospital, at a sports match, on a film set, etc.) to cheer them up or support them.

Typical contexts:

Bringing snacks to coworkers working overtime.
Bringing drinks/snacks to a sports team during practice or a game.
Bringing fruit or sweets to someone in the hospital.

It’s not normally used for:

Birthday/Christmas presents (→ プレゼント, 贈り物)
Romantic gifts

So 差し入れのケーキ is “cake that someone brought as a treat for the people working (as overtime support)” rather than a personal gift just for the speaker.

Why is it 差し入れのケーキ and not ケーキの差し入れ, or just ケーキ?

All three can be used, but the nuance/order changes slightly.

差し入れのケーキ
- Literally “treat-type cake” / “cake (that was) a 差し入れ”.
- Focus is on the cake itself, while clarifying what kind of cake it was.
- Feels natural in this context: the relevant thing is that cake was brought as a 差し入れ.
ケーキの差し入れ
- More like “a 差し入れ of cake”.
- Focus slightly more on the act/type of 差し入れ: “the 差し入れ (which was cake)”.
- Often used in phrases like:
  - ケーキの差し入れをいただきました。 – I received a cake as a treat (someone brought cake for us).
Just ケーキ
- Loses the idea that this was a special “treat for people working”.
- It would just sound like “(someone) brought cake”.

In this sentence, 差し入れのケーキ nicely keeps both pieces of information: it was cake, and it was brought as a supportive treat.

What does 持って来てくれて mean exactly, and how is it different from just 持って来ました?

Breakdown:

持って来る = “to bring (something) (to here)”
- 持って = the て-form of 持つ (“to hold/carry”)
- 来る = “to come”
持って来て = て-form of 持って来る
くれる = “to give (me/us)” / “to do (something) for me/us”

So:

持って来てくれる
= “to come bringing (it) for me/us”
= “to bring (something) (here) for us”

The くれる adds the nuance that the action is done for the benefit of the speaker (or the speaker’s in-group). This matches the feeling of gratitude that leads into とても嬉しかったです.

Compare:

先輩がケーキを持って来ました。
“My senpai brought cake.” (just a neutral description)
先輩がケーキを持って来てくれました。
“My senpai brought cake for us (for me).” (stronger sense of kindness)

The original uses 持って来てくれて、…嬉しかったです.
That structure:

Vてくれて、嬉しかったです。
“Someone did X for me, and I was happy (about it).”

is a very common pattern to express gratitude/pleasure about what someone did for you.

Who is the subject of くれて in 先輩が…持って来てくれて?

The subject is still 先輩.

Structure:

先輩が [ケーキを持って来てくれて]、とても嬉しかったです。

Inside the brackets:

先輩がケーキを持って来てくれて
= “(Senpai) brought cake for me/us”

Even though くれる is a giving verb that encodes “for me/us”, the doer of the action is the same が-marked subject:

Aさんが本を貸してくれた。
A gave (me) the favor of lending me a book. → A is the subject.

So in this sentence, 先輩 is the one “doing the favor” of bringing the cake.

Why is it 持って来て with two verbs instead of just one verb like 来て?

Japanese often combines a verb of manner with a verb of motion:

行く – to go
来る – to come
持つ – to hold/carry
持って行く – to take (something) (to there)
持って来る – to bring (something) (to here)

In 持って来る, the idea is:

持つ = “hold/carry”
do that, and then
来る = “come (to where I am / to the place being talked about)”

So ケーキを持って来る literally: “come bringing cake” → idiomatically: “bring cake (here)”.

Just 来る would be only “come”, with no information about what is being brought.

先輩が来てくれた。 – My senpai came (for me).
先輩がケーキを持って来てくれた。 – My senpai brought cake (for me/us).

Why is it 嬉しかったです and not 嬉しかったでした?

嬉しい is an い-adjective, and い-adjectives form the polite past like this:

嬉しい → 嬉しかったです

Pattern:

Present casual: 嬉しい
Past casual: 嬉しかった
Present polite: 嬉しいです
Past polite: 嬉しかったです

You do not say 嬉しかったでした. That’s ungrammatical because い-adjectives already contain the “be” part; you don’t add でした to the past form.

Compare with a noun or な-adjective:

元気だ → 元気でした (past polite)
学生だ → 学生でした (past polite)

So:

Correct: とても嬉しかったです。
Wrong: とても嬉しかったでした。

Why is there no “I” (私) in とても嬉しかったです?

Japanese often omits pronouns (like “I”, “you”, “he”, “she”) when they’re obvious from context.

Here, the speaker is clearly talking about their own feelings in reaction to senpai bringing cake. In such a situation, the default “owner” of 嬉しい (“to be happy”) is the speaker.

So とても嬉しかったです。 is naturally understood as:

“I was very happy.”

You could say:

私はとても嬉しかったです。

but in everyday Japanese, 私は is usually dropped unless:

You need to contrast with someone else (“As for me, I was happy, but he wasn’t”), or
The subject isn’t clear from context.

In neutral storytelling like this, leaving out 私 is more natural.

What nuance does とても add? Could I replace it with something like すごく or 本当に?

とても is a standard, neutral adverb meaning “very”.

とても嬉しい – very happy

You can replace it with other intensifiers, each with a slightly different feel:

すごく嬉しかったです。
- Colloquial, casual-feeling, often used in speech.
- “I was really/so happy.”
本当に嬉しかったです。
- Emphasizes genuineness/sincerity: “I was truly/really happy (from the bottom of my heart).”
めちゃくちゃ嬉しかったです / めっちゃ嬉しかったです。
- Very casual, slangy; avoid in formal writing.

In this sentence, とても嬉しかったです is polite and neutral, suitable for most situations (even semi-formal ones).