kyou ha sono naka no hitotu wo naikensuru yotei desu.

今日は sets today as the topic: As for today, ...

Using は is very common when giving information about what is planned, happening, or true for that day. It gives the sentence a natural topic-comment structure:

• 今日は = as for today
• その中の一つを内見する予定です = I plan to view one of those

If you used 今日が, it would sound like you were specifically identifying today in contrast to some other day, which is not the basic feel here.

その中の一つ literally means one of those / one among them.

Breakdown:

• その = that
• 中 = inside, among, within
• の = links nouns
• 一つ = one (thing)

So:

• その中 = among those / in that group
• その中の一つ = one of them

This is a very common pattern:

• A の中の B = B among A, or B out of A

Examples:

• 三人の中の一人 = one of the three people
• 候補の中の一つ = one of the options

The の connects 中 to 一つ and turns the phrase into something like one within that group.

Compare:

• その中 = among them / inside that
• その中の一つ = one of those

This is a very standard structure in Japanese. The の works a bit like of in English, though not always exactly.

So you can think of:

• その中の一つ = one of those
• literally: one belonging to that group

一つ is a very common general counter for one thing when the item is being referred to in a broad or non-technical way.

Here, 一つ sounds natural because it means one item / one option / one of them.

Why not the others?

• 一個 usually counts small concrete objects and can sound more physical
• 一 by itself does not work naturally here as a standalone noun
• 一つ is the most flexible and natural choice for one of the options

So in a sentence about choosing one property from a group, 一つ fits very well.

を marks the direct object of 内見する.

So the thing being viewed is:

• その中の一つを = one of them

Then:

• 内見する = to inspect/view (a property)

Together:

• その中の一つを内見する = to view one of them

Even though 一つ is a general word meaning one thing, here it clearly refers to one property/listing/home from the context.

内見する means to inspect/view a property, especially in real estate.

It refers to going to see the inside of an apartment, house, or other property before renting or buying it.

This word is common in housing and real estate contexts. A native speaker would naturally understand that the speaker is talking about a property viewing.

Related words:

• 内見 = property viewing / inspection
• 部屋を内見する = to view an apartment room
• 物件を内見する = to inspect a property

So this sentence strongly suggests the topic is housing or real estate.

内見します means I will view it / I’m viewing it.

内見する予定です means I plan to view it.

So 予定です adds the nuance that this is a plan or schedule, not simply a direct future statement.

Compare:

• その中の一つを内見します。
  = I will view one of them.

• その中の一つを内見する予定です。
  = I’m planning to view one of them.

The second one is slightly softer and more about intention or arrangement.

予定です means is scheduled / is planned.

It often follows a dictionary-form verb:

• verb dictionary form + 予定です

So here:

• 内見する = to view
• 内見する予定です = plan to view / am scheduled to view

Other examples:

• 行く予定です = I plan to go
• 会う予定です = I plan to meet
• 引っ越す予定です = I plan to move

This is one of the most useful beginner-intermediate grammar patterns for talking about plans.

Japanese often leaves out subjects when they are understood from context.

So even though there is no explicit 私 or 僕, the sentence naturally means something like:

• I plan to view one of them today

The subject is omitted because it is obvious in normal conversation. This happens constantly in Japanese.

If you wanted to make it explicit, you could say:

• 私は今日、その中の一つを内見する予定です。

But in most situations, that would be unnecessary.

Because Japanese often relies heavily on context.

If the speaker and listener have already been talking about apartments, houses, or listings, then その中の一つ naturally means one of those properties.

English often prefers to repeat the noun:

• I plan to view one of those apartments today.

Japanese often avoids repeating information when it is already clear:

• 今日はその中の一つを内見する予定です。

This makes the sentence sound natural rather than vague in context.

Yes. In normal Japanese writing, it would usually be written without spaces:

今日はその中の一つを内見する予定です。

Japanese normally does not use spaces between words the way English does. Learning materials often add spaces to make the structure easier to see.

Yes, depending on the context.

• この中の一つ = one of these
• その中の一つ = one of those
• あの中の一つ = one of those over there / one among those

The choice depends on how the speaker sees the items in relation to the speaker and listener.

Very roughly:

• この = near me / what I’m currently presenting
• その = near you / what you just mentioned / something already under discussion
• あの = over there / distant from both of us

In this sentence, その suggests that set we were talking about.

Yes. It is polite because it ends with です.

• 内見する予定です = polite
• 内見する予定だ = plain / less formal

The verb before 予定 stays in dictionary form, which is normal in this grammar pattern. The politeness comes from the final です.

So this sentence is appropriate in everyday polite conversation.