Learn Hardcore Japanese: kare no hyouzyou wo mite iru to, nani mo iwanakute mo kibun ga yoku wakatte kimasu. - When I watch his expression, I come to understand his mood well even without him saying anything.

ている here is the “progressive” form (an ongoing action: be looking), and と adds the nuance “whenever that state happens, the following result naturally happens.”

Compare:

彼の表情を見ると…
“When I look at his expression (once / in general), …”
彼の表情を見ていると…
“When I’m (there) looking at his expression / as I keep looking, …”

The ていると version sounds more like an ongoing observation that naturally leads to the realization in the second half of the sentence.

Who is the subject in this sentence? Why is 私 (I) not written?

Japanese often leaves out the subject when it is obvious from context. In this sentence:

彼の表情を見ていると、何も言わなくても気分がよく分かってきます。

there is no explicit 私 or あなた, but the most natural understood subject is:

(私は) “I (the speaker)”

So the full version would be:

（私は）彼の表情を見ていると、何も言わなくても気分がよく分かってきます。
“When I look at his expression, I can (gradually) understand how he feels even if he doesn’t say anything.”

In actual Japanese, saying 私は here would sound a bit heavy or unnecessary unless you needed to contrast me with someone else. Context usually makes it clear who is doing the looking and understanding.

What is the difference between 表情 and 顔? Why use 表情 here?

顔 (かお) = “face” (the physical face itself)
表情 (ひょうじょう) = “facial expression,” “look,” “expression on someone’s face”

表情 focuses on the expression that shows feelings, not just the face as an object.

So:

彼の顔を見る
“Look at his face” (physically looking at his face)
彼の表情を見る
“Look at his expression” = pay attention to what his face is expressing (sad, happy, worried, etc.)

Because the sentence is about understanding his mood/feelings from his face, 表情 is the natural choice.

Why is 表情 followed by を? What is 表情を見ている exactly saying?

表情を見ている is:

表情 = expression
を = direct object marker
見ている = be looking (at)

So 表情を見ている means “(I am) looking at (his) expression.”

In Japanese:

The thing you look at takes を with 見る:
- 空を見ます – “(I) look at the sky”
- テレビを見る – “watch TV”
- 彼の表情を見る – “look at his expression”

Using で or another particle here would be wrong; 見る takes its object with を.

What does 何も言わなくて mean? How does 何も work with a negative?

何も is typically used together with a negative and means “anything” / “nothing” depending on translation:

何も + negative verb = “not … anything / … nothing”

Examples:

何も分かりません。 – “I don’t understand anything.”
彼は何も言わない。 – “He doesn’t say anything.”

In this sentence:

何も言わなくて = “not say anything,” “without saying anything”

So 何も emphasizes “not even a single thing / not anything at all.” It’s stronger than just 言わなくて; it makes it clear there are no words at all, no information given verbally.

Why is it 言わなくても and not just 言わない? What does ～なくても mean?

言わなくても comes from:

言わない = not say
言わなくて = the て-form of 言わない
言わなくて + も = 言わなくても

～なくても has the meaning “even if (someone) doesn’t … / even without …” or often just “without …” in natural English.

So:

何も言わなくても
≈ “even if he doesn’t say anything”
≈ “without him saying anything”

It introduces a concession:

“Even though he doesn’t say anything (at all), I still come to understand his mood.”

This is more expressive than just 何も言わない (“he doesn’t say anything”) because it directly ties the “not saying” to the result that follows.

What is the nuance of 気分が here? Why が and not を or は?

気分が is:

気分 = mood, feeling (often temporary physical/mental state)
が = subject marker

With 分かる, the thing that is understood normally takes が, not を:

日本語が分かる – “I understand Japanese.”
気持ちが分かる – “I understand (your) feelings.”
気分が分かる – “I understand (your) mood / how you feel.”

So 気分が分かる is literally “(his) mood is understood” rather than “I understand his mood” grammatically, but in English we translate it the other way around.

は could appear if we were contrasting or topicalizing, e.g.:

彼の気分はよく分かってきます。
“As for his mood, I really come to understand it well.”

But the default, neutral way with 分かる is to mark the thing understood with が.

Does 気分がよく mean “in a good mood” here? Or is よく modifying 分かってきます?

Here よく is an adverb meaning “well” / “clearly / thoroughly”, and it modifies 分かってきます, not 気分.

The structure is:

気分が｜よく分かってきます
- 気分が – (his) mood (subject)
- よく – well, clearly (adverb)
- 分かってきます – comes to be understood

So the meaning is:

“(I) come to understand his mood well / clearly.”

If you wanted to say “be in a good mood”, you would say something like:

気分がいい – “(to) be in a good mood / feel good”
気分がよくなる – “(to) get into a good mood / start feeling good”

In those, よく (or いい) is an adjective describing the quality of the mood.
In our sentence, よく modifies 分かってきます and describes the degree of understanding.

What is the function of 分かってきます instead of just 分かります? What does ～てくる add?

分かってきます is:

分かる = to understand, become clear
分かって = て-form
分かってくる = “to come to understand,” “to gradually become understood”
分かってきます = polite form

The pattern ～てくる often expresses:

A change or development over time that moves toward the present or toward “me”:
- だんだん寒くなってきました。 – “It has gradually become cold.”
A process of gradually realizing or coming to feel something:
- 意味が分かってきた。 – “I’ve started to understand the meaning / It’s become clearer to me.”

So 気分がよく分かってきます means something like:

“His mood gradually becomes very clear (to me).”
“I come to understand his mood well (as time passes / as I look).”

If you said 気分がよく分かります, it would be more like:

“I understand his mood well (in general).”

分かってきます adds the nuance of process / gradual realization rather than a simple, static ability.

Could you say 気分がよく分かります instead? How would the meaning change?

Yes, you could say:

彼の表情を見ていると、何も言わなくても気分がよく分かります。

This would still be natural and understandable. The nuance is:

気分がよく分かります
→ “I (can) understand his mood well.”
(States the ability / fact, not focusing on the process.)
気分がよく分かってきます
→ “I come to understand his mood well / it becomes clear to me.”
(Emphasizes that, as you keep looking, his mood gradually becomes clearer.)

So the original with 分かってきます better matches the idea of watching his expression and gradually picking up on how he feels.

Is きます here the same 来ます as “come”? Why is the polite form used?

Yes, grammatically it is the same verb 来る (くる) in its polite form 来ます (きます), but:

As an auxiliary after the て-form (～てくる), くる is often used in a more abstract way:
- To show a change or movement toward the present or the speaker, rather than a literal physical “come here.”

So in 分かってきます, there is no physical “coming.” It means “(the understanding) comes to me / develops up to now.”

Politeness:

分かってくる = plain
分かってきます = polite (～ます form)

The whole sentence is in polite style (～ます) because that’s the default neutral–polite register in many textbooks and everyday conversation with people you’re not very close to.

Why is the non-past tense (分かってきます) used? Is this talking about the future or about a general fact?

Japanese non-past (the ～ます／～る form) covers:

Simple present
Habitual / general truths
Near future

Here, 分かってきます expresses a general pattern:

“When I look at his expression, (I) come to understand his mood well (like this, as a rule).”

It’s not a specific past event but something that happens generally or repeatedly. That’s why non-past is natural.

If you wanted to talk about a specific past situation, you might say:

彼の表情を見ていると、何も言わなくても気分がよく分かってきました。
“As I was looking at his expression, I came to understand his mood well.”

So the non-past in the original sentence is best understood as describing a habitual or general tendency, not a single one-time future event.