sono sensei ha kibisisou ni mieru keredo, zissai ha totemo sinsetu desu.

Not quite.

• 厳しい = strict
• 厳しそう = looks strict / seems strict

The ending -そう here means “seems” or “looks like” based on appearance or impression.

So:

• その先生は厳しい。
  = That teacher is strict.
• その先生は厳しそう。
  = That teacher looks strict.

In your sentence, the speaker is saying that the teacher gives the impression of being strict, but that impression is different from reality.

No. Japanese has two common そう patterns, and they mean different things.

1. Appearance / seeming

Used in your sentence:

• 厳しそう = looks strict
• おいしそう = looks delicious

This is based on what something seems like from appearance or impression.

2. Hearsay

• 雨が降るそうです = I hear that it will rain

This means “I heard that...”

So 厳しそう in your sentence is the appearance/seeming use, not the hearsay use.

Because 見える here works with an adverb-like form meaning “appears in a ... way.”

• 厳しそう acts like a な-adjective
• To modify the verb 見える, it becomes 厳しそうに

So:

• 厳しそうに見える = appears to be strict / looks strict

This is similar to how な-adjectives change before verbs:

• 静かだ → 静かに話す
• 親切だ → 親切に教える

Even though 厳しそう comes from an adjective, in this pattern it behaves like something that can take に before a verb.

Because だ is not used before に in this structure.

When a な-adjective-like word modifies a verb, you use に, not だに.

So:

• 厳しそうだ = It seems strict.
• 厳しそうに見える = It looks strict.

The だ appears when 厳しそう is the main predicate of the sentence, but not when it modifies 見える.

Here, 見える means “to look,” “to appear,” or “to seem.”

It does not literally mean only “to be visible.”
Japanese 見える can mean:

• something can be seen / is visible
• something appears a certain way

In this sentence:

• 厳しそうに見える = appears strict / looks strict

So the teacher may give that impression, even if the reality is different.

Yes, but the nuance is a little different.

厳しそうに見える

• looks like they are strict
• gives the impression of being strict
• often based on appearance or vibe

厳しく見える

• looks strict / appears strict
• a bit more direct
• sometimes sounds more like “comes across as strict”

In many cases they are similar, but 厳しそうに見える emphasizes the speaker’s impression a little more clearly.

This is very common in Japanese.

Japanese often uses:

• plain form in the middle of a sentence
• polite form at the end of the sentence

So:

• 見えるけれど = plain form in a non-final clause
• 親切です = polite ending

This is natural Japanese. You could think of the politeness level being decided mostly by the sentence ending.

A fully plain version would be:

• その先生は厳しそうに見えるけれど、実際はとても親切だ。

A more consistently polite version might be:

• その先生は厳しそうに見えますけれど、実際はとても親切です。

But the original sentence is perfectly natural.

けれど means “but,” “though,” or “although.”

It connects two ideas that contrast:

• 厳しそうに見える = the teacher looks strict
• 実際はとても親切です = actually, the teacher is very kind

So the contrast is:

looks strict, but is actually kind

Compared with でも or しかし, けれど often feels a bit softer and smoother inside a sentence.

Related forms:

• けど = more casual
• けれど = standard
• けれども = slightly more formal/literary

The は adds a contrastive/topic nuance.

• 実際 = in reality / actually
• 実際は = as for reality / in reality, though

It helps set up a contrast between:

• outward appearance: 厳しそうに見える
• real situation: 実際はとても親切です

So は is doing something like:

• “As for the actual reality...”
• “But in fact...”

It makes the contrast clearer.

Usually not in this sentence.

実際は

means “in reality / actually” and contrasts appearance with truth.

実際に

usually means “actually, in practice,” “really,” or “in actual action” and often modifies a verb.

For example:

• 実際に会った。 = I actually met them.
• 実際に使ってみた。 = I actually tried using it.

In your sentence, the point is contrast, so 実際は is the natural choice.

親切 is a な-adjective.

So:

• 親切な先生 = a kind teacher
• 先生は親切です = the teacher is kind

That is why the sentence ends with:

• とても親切です

If it came before a noun, it would need な:

• とても親切な先生です

Because な is only used when a な-adjective comes before a noun.

Compare:

Before a noun

• 親切な先生 = a kind teacher

As the predicate

• 先生は親切です = the teacher is kind

So in your sentence, 親切 is the predicate, so no な is needed.

その means “that” and usually refers to something near the listener, or something already mentioned.

Japanese demonstratives are:

• この = this
• その = that
• あの = that over there

So:

• この先生 = this teacher
• その先生 = that teacher
• あの先生 = that teacher over there

In isolated example sentences, その often just means “that teacher” in a general conversational sense, especially if the teacher has already been mentioned.

They are only there to help learners read the sentence.

Normal Japanese is usually written without spaces:

その先生は厳しそうに見えるけれど、実際はとても親切です。

So don’t assume each space marks a completely separate “word” in the same way English does. They are mainly a teaching aid here.

Yes, とても means “very.”

It can modify both い-adjectives and な-adjectives, and also adjective-like forms such as 厳しそう.

Examples:

• とても厳しい = very strict
• とても親切 = very kind
• とても厳しそう = looks very strict

In your sentence, it modifies 親切:

• とても親切です = is very kind

Because Japanese often omits information that is already understood from context.

The sentence starts with:

• その先生は = as for that teacher

After that, the subject/topic is already clear, so the second half does not need to repeat it.

A fuller English-like version would be:

• That teacher looks strict, but in reality, that teacher is very kind.

Japanese usually avoids that repetition unless it is needed for emphasis or clarity.

Yes, it can, especially in conversation, where it may sound softer or leave something implied.

For example:

• 厳しそうに見えるけれど…。

This can feel like:

• “He looks strict, but...”
• “He looks strict, though...”

The speaker may be inviting the listener to respond, or softening what they are saying.

In your sentence, though, けれど simply connects to the next clause in the normal way.

A useful pattern is:

• [adjective stem] + そうに見える
  = to look/seem [adjective]

Examples:

• おいしそうに見える = looks delicious
• 難しそうに見える = looks difficult
• 元気そうに見える = looks healthy / energetic
• 厳しそうに見える = looks strict

This pattern is very common when talking about first impressions or outward appearances.

Yes, that is a natural implication.

The structure:

• looks strict, but actually very kind

suggests that the teacher’s appearance or first impression does not match reality.

So the sentence carries the nuance:

• “At first you might think this teacher is strict, but in fact they’re very kind.”

That contrast is an important part of the sentence’s meaning and tone.