Learn Hardcore Japanese: kinou no bangumi de ninki no kasyu ni intabyuu wo simasita. - I did an interview with a popular singer on yesterday’s program.

昨日の番組
- Literally: “yesterday’s program/show”
- Here, 昨日 (yesterday) is acting like a noun, and の shows a loose “belonging / related to” relationship:
  - the show of yesterday → the show that was on yesterday
- This is similar to English “yesterday’s show”.
人気の歌手
- Literally: “popularity’s singer” → “popular singer”
- 人気 (popularity) is a noun, and の links it to 歌手 (singer).
- Functionally, this の often works like an adjective marker: 人気の歌手 = a singer who is popular / a popular singer.

So grammar-wise it’s the same の (“noun A の noun B”), but:

In 昨日の番組, の is more like “X’s Y / Y of X”.
In 人気の歌手, の is more like “Y that has X / Y characterized by X”, effectively turning 人気 into an adjective-like modifier.

Why is で used in 番組で? Why not に?

で marks the place or setting where an action happens.

番組でインタビューをしました
- “(I) did an interview on the show / during the program.”

Here, the show is treated as the venue/occasion where the interview took place, just like:

学校で勉強しました – “I studied at school.”
会議で発表しました – “I gave a presentation at the meeting.”

If you used 番組に here, it would sound more like:

“(I) did an interview to the show” (which is odd; you interview people, not shows).

So:

場所・場面 where an action occurs → で
Target of an action (person/thing affected) → often に

In this sentence, the “place/occasion” is the 番組, so で is correct.

Why does the singer use に: 人気の歌手にインタビューをしました? In English, we “interview someone” and they’re a direct object.

English and Japanese structure this differently.

In Japanese:

インタビューをする = “to do an interview” (literally)
The person you interview is seen as the target of that action, so they get に.

So:

人気の歌手にインタビューをしました
= “(I) did an interview to/with a popular singer” = “(I) interviewed a popular singer.”

Pattern:

彼にインタビューをしました – “I interviewed him.”
有名人にインタビューをしたいです – “I want to interview a celebrity.”

に here marks the person you direct the interview toward, while を marks the thing you did (インタビュー).

What is the role of を in インタビューをしました? Can you drop it and just say インタビューしました?

インタビューをする is a standard suru-verb pattern: noun + を + する.

インタビュー (noun) = interview
インタビューをする = to do an interview → to interview

So を marks インタビュー as the object of する.

You can also say:

インタビューしました

In many everyday contexts, インタビューをしました and インタビューしました feel almost the same. The を is often omitted in casual speech with する-verbs. Using を is a bit more complete/explicit and is always safe, especially in writing or more formal speech.

Who is the subject in this sentence? There is no I or we—how do we know who did the interview?

Japanese often omits the subject when it’s clear from context.

昨日の番組で人気の歌手にインタビューをしました。

By default, if you say this about your own actions in a normal conversation, it’s usually understood as:

“I interviewed a popular singer on yesterday’s show.” or
“We (e.g. our show/team) interviewed a popular singer on yesterday’s program.”

To make the subject explicit, you could say:

私は昨日の番組で人気の歌手にインタビューをしました。
(“I interviewed …”)
私たちは昨日の番組で人気の歌手にインタビューをしました。
(“We interviewed …”)

But in natural Japanese, if the subject is obvious from context, it’s normally left out.

Does 昨日 mean the interview happened yesterday, or just that the program was yesterday? Could it mean both?

As written:

昨日の番組で人気の歌手にインタビューをしました。

The most natural reading is:

“(On) yesterday’s program, (we) interviewed a popular singer.”

That implies:

The program itself (broadcast) was yesterday.
The interview is part of that program, so it also happened in that context.

If you wanted to clearly say “Yesterday, on the program, we interviewed…”, with yesterday modifying the time of the action rather than the program, you’d typically say:

昨日、番組で人気の歌手にインタビューをしました。
(“Yesterday, on the show, we interviewed a popular singer.”)

So:

昨日の番組で … = on yesterday’s program (focus on the program’s date).
昨日、番組で … = yesterday, on (the) program (focus on when you did it).

Why is it 昨日の番組 and not 昨日に番組?

Two points:

昨日 as a time word
- Many time words (昨日, 今日, 明日, 毎日, 先週, 来年, etc.) are usually used without に:
  - 昨日行きました – “I went yesterday.”
  - 明日行きます – “I’ll go tomorrow.”
- 昨日に行きました is possible, but sounds more marked/unusual; 昨日行きました is the norm.
Using の to modify a noun
- 昨日の番組 = “yesterday’s program” (the program that was on yesterday).
- Here, 昨日 is being used like a noun modifying another noun:
  - X の Y = Y related to X → “the show of yesterday.”

So 昨日に番組 doesn’t work because:

に is not used to connect two nouns like that.
You want “yesterday’s program”, not “program at yesterday”.

Correct patterns:

昨日の番組 – “yesterday’s program”
昨日、番組を見ました – “Yesterday, I watched the program.”

Can I change the word order, like 人気の歌手に昨日の番組でインタビューをしました? Does it change the meaning?

You can change the word order quite flexibly in Japanese as long as you keep the particles attached to the right words. For example:

昨日の番組で人気の歌手にインタビューをしました。
人気の歌手に昨日の番組でインタビューをしました。
人気の歌手にインタビューを昨日の番組でしました。

All can be grammatically acceptable, and the basic meaning remains:

“(We) interviewed a popular singer on yesterday’s program.”

The differences are in focus/emphasis:

Starting with 昨日の番組で … puts slight focus on “as for yesterday’s show…”.
Starting with 人気の歌手に … slightly highlights “to a popular singer…”.
Moving 昨日の番組で later can make it feel more like extra information being added.

But overall, the sentence is understandable and the core meaning doesn’t change.

Why is the verb in past tense しました if the word 昨日 already shows that it’s in the past?

In Japanese, time expressions (like 昨日, 来年, さっき, etc.) and verb tense are independent. You still need to put the verb in the correct tense:

昨日行きました – “I went yesterday.” (past)
明日行きます – “I will go tomorrow.” (non-past)

If you said:

昨日行きます – literally “I go tomorrow (but using a non-past form)”

this could sound wrong or at least confusing.

So in your sentence:

昨日の番組で人気の歌手にインタビューをしました。

昨日 sets the time frame. しました shows that the action is completed/past. Both are needed for a natural sentence.

What is the politeness level of しました here? How would it change if I said した instead?

しました is the polite past form of する.

インタビューをしました。
→ polite: what you’d normally use with people you’re not very close to, in work, public, or formal contexts.

If you use した:

インタビューをした。

That’s the plain past form. It’s used:

With friends, family, or people of lower status (e.g., a teacher writing notes to themselves, manga internal monologue).
In casual speech and in many written narratives (novels, blogs, etc., depending on style).

Meaning-wise:

Both = “(I/we) interviewed (someone).”
The difference is politeness/register, not the core meaning.