How do you say that something does not exist in Japanese?
For example, if I wanted to say "Unicorns don't exist" how would I say this in Japanese? Is ユニコーンがありません natural or is there a better way to say it?

Please use romaji in your answer if you use any kanji so I can learn the kanji and pronunciation.

ありがとうございます

Question

How do you say that something does not exist in Japanese?
For example, if I wanted to say "Unicorns don't exist" how would I say this in Japanese? Is ユニコーンがありません natural or is there a better way to say it?

Please use romaji in your answer if you use any kanji so I can learn the kanji and pronunciation.

ありがとうございます

Answer

Hi, I'm Shu Chen. Japanese is not my first language, but I have been living in Tokyo for 7 years. Maybe I can help you with your question.

I think 
ユニコーンは存在sonzaiしません
or
ユニコーンは実在jitsuzaiしません
are better.

Hopefully above answer helps:)

Answer

ユニコーン／一角獣（IKKAKUJUU)は、いません／存在しません。

I personally would say

"ユニコーン／一角獣は架空（KAKUU)の生物(SEIBUTSU)です。"

Answer

I agree with Shu Chen. I would say:

ユニコーンが存在しません。OR ユニコーンがいません。

Keep in mind that with animals (even imaginary ones), you must use the verb いる and not ある. ある is used for inanimate objects.

Answer

I would also say "ユニコーンは実在(jitsuzai)/存在（sonzai)しません。", rather than "ユニコーンが実在/存在しません。"

When you use a particle が in this sentence, it strickes me that (as if unicones should exist, but) they don't currently exist here in my imprresion.

I hope it will be a help for you.