kougei ha omosiroi desu.

A common reading is:

こうげい は おもしろい です。

• 工芸 = こうげい
• は is written ha but pronounced wa here because it is the topic particle
• 面白い = おもしろい
• です = desu

So the full sentence is read:

こうげい は おもしろい です。

When は is used as the topic particle, it is pronounced wa.

So in this sentence:

• 工芸は = As for crafts / Speaking of crafts

This is a very common thing in Japanese:

• written: は
• pronounced: wa

But when は is part of a word, it is usually pronounced ha.

は marks the topic of the sentence.

In 工芸 は 面白い です, the topic is 工芸. The sentence is saying something about crafts.

A natural way to think about it is:

• As for crafts, they are interesting.
• or more naturally in English: Crafts are interesting.

The important thing is that は does not exactly mean English is/are. It marks what the sentence is about.

Japanese does not always need a separate verb like English is/are in the same way.

Here, 面白い is an i-adjective, and i-adjectives can act like the main predicate of a sentence by themselves.

So:

• 工芸は面白い。 = Crafts are interesting.

The です at the end adds politeness, but it is not exactly the same as the English verb to be here.

So the sentence works because:

• 工芸 = topic
• 面白い = predicate adjective
• です = polite ending

Because 面白い is an i-adjective.

For i-adjectives, the final い is part of the word, so you keep it:

• 面白いです ✔
• 面白です ✘

This is different from na-adjectives and nouns, which take です more directly:

• 静かです
• 学生です

But with an i-adjective like 面白い, you do not remove the い in the plain affirmative form.

Here, です mainly makes the sentence polite.

Compare:

• 工芸は面白い。 = plain style
• 工芸は面白いです。 = polite style

So after an i-adjective, です does not change the basic meaning very much. It mostly changes the register.

This is why learners often hear that です is not always literally is/am/are. In this sentence, it is better to think of it as a polite sentence ending.

面白い is an i-adjective.

That means:

• it ends in い
• it can directly describe a noun, as in 面白い本 = an interesting book
• it can also end a sentence, as in 工芸は面白い

It also changes form by itself:

• 面白い = interesting
• 面白くない = not interesting
• 面白かった = was interesting
• 面白くなかった = was not interesting

This is one reason i-adjectives are important to learn early.

Yes, but it has a slightly different nuance.

• 工芸は面白いです = As for crafts, they are interesting
• 工芸が面白いです = Crafts are the interesting thing / It is crafts that are interesting

In many situations, は is the more neutral choice when introducing the topic.
Using が can sound more selective, contrastive, or focused depending on context.

For a simple beginner sentence, 工芸は面白いです is very natural.

It can be understood either way depending on context.

Japanese nouns usually do not have a built-in singular/plural distinction the way English nouns do. So 工芸 could mean:

• craft
• crafts
• craftsmanship
• the craft arts

In English, the translation will depend on what sounds natural in context.

Yes, it is grammatically natural.

It is a simple, polite sentence of the pattern:

[topic] は [i-adjective] です

Examples of the same pattern:

• 日本語は難しいです。
• この本は面白いです。
• 冬は寒いです。

That said, in real conversation, a speaker might choose a more specific word depending on what they mean by 工芸, but the sentence itself is perfectly fine as a basic example.

Yes, if it is already understood from context.

Japanese often leaves out information that is obvious. So if everyone already knows you are talking about crafts, someone might simply say:

面白いです。

That would still mean It’s interesting or They’re interesting, depending on context.

Japanese relies heavily on context, much more than English does.

You change the i-adjective 面白い to its negative form:

• 工芸は面白くないです。
• 工芸は面白くありません。

Both mean Crafts are not interesting.

A quick breakdown:

• 面白い → 面白くない
• then you can keep polite style with です
• or use the more formal negative style 面白くありません

Both are common, though 面白くないです is very common in everyday speech.

You would usually drop です:

工芸は面白い。

That is the plain form.

So the contrast is:

• 工芸は面白いです。 = polite
• 工芸は面白い。 = plain / casual

The meaning stays basically the same. The difference is the level of politeness.