onsenmanzyuu wo taberu.

No. In standard modern Japanese, 食る is not correct here.

The verb should be 食べる (たべる), so the natural sentence is:

温泉まんじゅうを食べる。

This is probably a typo or an omitted べ.

食べる is an ichidan verb meaning to eat. Its dictionary form is 食べる.

With the corrected verb, it is read:

おんせんまんじゅう を たべる。

More naturally, without spaces:

おんせんまんじゅうをたべる。

A few reading notes:

• 温泉 = おんせん
• まんじゅう stays in hiragana here
• を is written を but pronounced お
• 食べる = たべる

So the full pronunciation is basically:

おんせんまんじゅう お たべる

を marks the direct object of the verb.

So in:

温泉まんじゅうを食べる

the thing being eaten is 温泉まんじゅう.

A very rough English-style breakdown is:

• 温泉まんじゅう = the thing
• を = marks it as the thing acted on
• 食べる = eat

So を is the particle that shows what the action is directly affecting.

Also, even though it is written を, in modern Japanese it is usually pronounced お.

Japanese often leaves out the subject when it is clear from context.

So 温泉まんじゅうを食べる could mean:

• I eat onsen manju
• I will eat onsen manju
• He eats onsen manju
• She is eating onsen manju

depending on the situation.

This is very normal in Japanese. If the speaker or topic is already understood, you do not have to say it.

If you wanted to include a topic, you could say:

• 私は温泉まんじゅうを食べる。 = As for me, I eat / will eat onsen manju.

Normally, Japanese is written without spaces.

So the usual written form would be:

温泉まんじゅうを食べる。

Spaces are often added in beginner materials to make the sentence easier to read and to show where words or particles begin and end.

So the spaced version is not necessarily wrong for teaching, but it is not the normal way Japanese is written in everyday text.

That is very common.

The full kanji form is:

温泉饅頭

But 饅頭 is often written as まんじゅう because:

• the kanji 饅頭 is not very common for beginners
• food names are often partly or fully written in hiragana
• mixed writing can look softer and more readable

So all of these can appear:

• 温泉まんじゅう
• 温泉饅頭

Both are fine.

食べる is the dictionary form and also the plain non-past form.

That means it can be used for:

• a general statement: eat / eats
• a future action: will eat

For example:

• 温泉まんじゅうを食べる。 = I eat / will eat onsen manju.

Japanese non-past verbs do not mark the future separately the way English often does. Context tells you whether it means present habitual or future.

No. 食べる is the plain form, not the polite form.

The polite version is:

温泉まんじゅうを食べます。

So:

• 食べる = plain
• 食べます = polite

The plain form is very common in casual conversation, dictionaries, and informal writing.

In this sentence, 温泉まんじゅう functions as one noun phrase.

It is a compound noun:

• 温泉 = hot spring
• まんじゅう = a kind of bun/sweet

Together, 温泉まんじゅう refers to the specific food called onsen manju.

So the object marked by を is the whole phrase:

温泉まんじゅうを

not just まんじゅう by itself.

Yes. The most natural correction is:

温泉まんじゅうを食べる。

That fixes the verb and removes the teaching-style spaces.

If you want a polite version:

温泉まんじゅうを食べます。

If you want to include the subject/topic:

私は温泉まんじゅうを食べる。
or
私は温泉まんじゅうを食べます。