Learn Hardcore Japanese: sono haiyuu no serihu no iikata ga sizen datta node, nihongo no benkyou ni mo ii eikyou ga arisouda to omoimasita. - The way that actor delivered his lines was so natural that I thought it might also have a good influence on my Japanese studies.

その俳優 – that actor
その俳優の台詞 – that actor’s lines (dialogue)
その俳優の台詞の言い方 – the way of saying that actor’s lines / the way that actor delivered his lines

So each の is basically working like the English “’s” or “of,” connecting nouns. Japanese can stack these to build detailed noun phrases.

Grammatically, the whole thing その俳優の台詞の言い方 is one noun phrase and functions as the subject of the sentence (marked by が).

Why is が attached to 言い方 and not to 俳優? Isn’t the actor the subject?

The subject of the sentence is not “the actor”; it’s the way of saying the lines:

Subject: その俳優の台詞の言い方
Subject marker: が

So:

その俳優の台詞の言い方が自然だった
The way that actor said his lines was natural.

Within that subject phrase, 俳優 is just part of a description (inside a “possessive” chain). The が comes after the head noun (言い方) of the noun phrase, not after the first noun in the chain.

What is the nuance of 自然だった here? Does it just mean “was natural”?

Yes, 自然だった literally means “was natural,” but in this context it means:

natural-sounding
not awkward or textbook-like
like how real native speakers would say it

So 台詞の言い方が自然だった suggests the actor’s delivery/intonation/choice of wording sounded like authentic everyday Japanese, not stiff or unnatural acting.

What is the difference between ので and から here? Could I say 自然だったから instead of 自然だったので?

You could say 自然だったから, and the meaning would still be “because the way he said it was natural…”.

Nuance:

ので – sounds a bit more formal, explanatory, and slightly softer/politer. Often used in writing, polite speech, or when you want to sound less direct.
から – more direct and conversational. Very common in casual speech.

So:

自然だったので、… – “Since it was natural, …” (polite/explanatory flavor)
自然だったから、… – “Because it was natural, …” (more everyday-casual tone)

What does 日本語の勉強に mean here, and why is the particle に used?

日本語の勉強に literally is “for Japanese study”:

日本語の勉強 – study of Japanese / Japanese studies (your studying of the Japanese language)
〜にいい / 〜に悪い – good for / bad for

So 日本語の勉強にいい影響がある means “to have a good influence on my Japanese study.”

The に marks the “target” or “beneficiary” of the influence: what is being affected.

What is the role of も in 日本語の勉強にも?

にも is に + も.

に – “for” (as above)
も – “also / too / even”

So 日本語の勉強にも suggests “on my Japanese studies as well,” implying:

there was/will be some good effect in another area (e.g., enjoyment, motivation, understanding the movie),
and
in addition to that, it also seems good for my Japanese studies.

It adds the nuance of “not only in one way/area, but also for my Japanese learning.”

What does いい影響がある mean as a set phrase?

いい影響がある literally is “there is a good influence.” Idiomatically, it means:

to have a positive effect
to influence (someone/something) in a good way
to be beneficial

So in context:

日本語の勉強にもいい影響がありそうだ
It seems like it will have a positive effect on my Japanese studies as well.

How does ありそうだ work grammatically, and what nuance does it add?

ありそうだ is:

ある (to exist) → あり (conjunctive form) + そうだ (“seems / looks like / likely” based on some basis)

So いい影響がありそうだ means:

“It seems like there will be a good influence.”
“It looks like it will have a good effect.”
“It’s likely to have a good influence.”

Nuance:

You’re not stating it as an absolute fact, but as a reasonable expectation or impression, probably based on how natural the speech was, how much you understood, etc.

Also, this is the “seems/looks/likely” そうだ, not the “I heard that” そうだ (hearsay).

Why is it と思いました and not just と思います?

Both are possible, but the nuance is different.

…と思いました (past) – “I thought that …”
You’re placing the thinking at a particular time in the past; e.g., while watching the movie or just after.
…と思います (present) – “I think that …”
You’re presenting it as your current opinion at the time of speaking.

Here, because the sentence describes a reaction you had when you experienced the actor’s performance, と思いました fits naturally: it’s a past thought resulting from that experience.

If I still think this now, why do Japanese speakers often use the past 思いました instead of the present?

In Japanese, even if you still think something now, it’s common to use the past when you’re:

telling a story,
recalling your first impression, or
describing what went through your mind at a specific moment.

Example nuance:

映画を見て、その俳優の台詞の言い方が自然だったので、…と思いました。
→ “When I watched the movie, I thought, ‘This will be good for my Japanese study too.’”

You’re reporting the original moment of realization. Whether you still believe it now is implied from context; Japanese doesn’t need to switch to present tense to show that.

Why is there no explicit “I” in the Japanese sentence?

Japanese often omits subjects like “I,” “you,” “he/she” when they’re clear from context.

In …と思いました, the default understood subject is “I” (the speaker). There is no need to say 私は unless you want to emphasize contrast (e.g., “I, at least, thought that…”).

This is very natural Japanese: pronouns are used less frequently than in English, especially when the subject is obvious.

Could the sentence start with the main clause, like 日本語の勉強にもいい影響がありそうだと思いましたので…?

Grammatically you could rearrange, but:

Reason clause + ので, then main clause is the most natural order:
自然だったので、〜と思いました。
Putting the main clause first with ので afterward is much rarer and sounds awkward or overly written/formal in many contexts.

You can say something like:

日本語の勉強にもいい影響がありそうだと思ったので、その映画を何度も見ました。
“Because I thought it seemed like it would be good for my Japanese studies, I watched that movie many times.”

Here, the ので is still linking a reason clause to a result clause; the reason clause comes first.

Could I say 台詞の言い方が自然に聞こえた instead of 自然だった? What’s the difference?

Yes, you could say:

その俳優の台詞の言い方が自然に聞こえたので、…

自然だった vs 自然に聞こえた:

自然だった – “was natural.”
You’re simply describing the way of speaking as natural.
自然に聞こえた – “sounded natural to me.”
This emphasizes your perception/experience (how it sounded to your ears).

Both are natural. 自然に聞こえた makes it slightly clearer that you’re talking about how it seemed from your perspective as a listener.