saisyo ha tokeimawari, tugi ha hantokeimawari da.

• 最初 = さいしょ
• 時計回り = とけいまわり
• 次 = つぎ
• 反時計回り = はんとけいまわり
• だ = da

So the whole sentence is read:

さいしょ は とけいまわり、つぎ は はんとけいまわり だ。

Here, は marks the topic or sets up a contrast.

So:

• 最初は = as for the first part / first,
• 次は = as for the next part / next,

This pattern is very common in instructions and explanations. It helps organize steps clearly:

• 最初は A
• 次は B

In English, this often corresponds to First, ... Next, ...

Because in this sentence they are not being used mainly as time/location markers. They are being used as topics in a sequence.

Compare:

• 最初に = first / at first / firstly
  This emphasizes order as an adverb.
• 最初は = as for the first one / first,
  This sets up a topic and often contrasts it with what comes next.

Similarly:

• 次に = next
• 次は = as for the next one / next,

In this sentence, は works well because the speaker is contrasting two stages:

• first: clockwise
• next: counterclockwise

時計回り means clockwise.

It is built from:

• 時計 = clock
• 回り = turning / rotation / direction of turning

So literally it is something like the direction a clock goes.

This is a very common word when giving instructions about rotating, turning screws, drawing circles, exercising, and so on.

反時計回り means counterclockwise.

It is made from:

• 反 = anti- / opposite
• 時計回り = clockwise

So literally it is opposite of clockwise.

This kind of word-building is common in Japanese. The prefix 反 often gives the idea of opposite or reverse.

Japanese often omits information that is clear from context.

This sentence is probably part of a larger instruction, such as:

• turning something
• rotating your body
• stirring
• drawing circles
• moving a dial

So the full idea might be something like:

• At first, do it clockwise; next, do it counterclockwise.

But Japanese can leave out what is being turned and which verb is being used if the context already makes it obvious.

That makes the sentence short and natural in instructional language.

だ is the plain form of the copula, similar to is in English.

In this sentence, it connects the topic to the description:

• 最初は時計回りだ
• 次は反時計回りだ

Because the sentence is compact, only one だ appears at the end, but it applies to the whole contrastive structure.

It gives the sentence a plain, direct tone. In more polite speech, you could say:

最初は時計回りで、次は反時計回りです。

or

最初は時計回り、次は反時計回りです。

Not really. Japanese often leaves out nouns when they are understood from context.

For example, depending on the situation, the speaker may really mean:

• the first rotation
• the first step
• the first time
• the next turn
• the next step

So 最初 and 次 can stand on their own when the situation is clear. English often needs to make things more explicit, but Japanese does not.

The comma helps separate the two contrasted parts:

• 最初は時計回り、
• 次は反時計回りだ。

It makes the sentence easier to read and shows a pause between the two stages.

Japanese commas are often used more flexibly than English commas. Here, the comma is very natural because the sentence is presenting two parallel pieces of information.

Yes. A very natural version is:

最初は時計回りで、次は反時計回りだ。

Here, で links the first phrase to the second.

Both versions are understandable, but the one with で can feel a little smoother because it explicitly connects the two parts. The version with just a comma is also common, especially in short instructions or notes.

Yes, 初めは could also be used in many contexts.

Very roughly:

• 最初 often means the first one / the beginning / the outset
• 初め also means the beginning / at first

In many everyday cases, they overlap. In a step-by-step instruction like this, 最初は sounds very natural because it clearly marks the first stage in a sequence.

So:

• 最初は時計回り、次は反時計回りだ。
• 初めは時計回りで、次は反時計回りだ。

Both can work, though 最初 often feels especially natural when contrasting first and next.

It is plain-style Japanese, so it is not polite in the です / ます sense.

That does not mean it is rude. It can sound perfectly normal in:

• instructions
• explanations
• notes
• informal speech
• manuals with concise wording

A more polite version would be:

最初は時計回りで、次は反時計回りです。

So the original is best thought of as plain and concise, not necessarily impolite.

Yes. In this sentence they behave like noun-like expressions.

That is why they can be followed by だ:

• A は 時計回りだ
• B は 反時計回りだ

Japanese has many expressions like this that can function as noun phrases or description phrases without needing an adjective or verb. In English we may translate them with adverbs like clockwise and counterclockwise, but in Japanese their grammar does not always match the English part of speech exactly.