Can a dash be horizontal in vertical text?

Hi,
I am designing a tattoo for myself and it involves Katakana, in terms of attractiveness I much prefer the'dash' to be horizontal, it fits a lot better in the space it will be tattooed, but I am very aware that this is not ever how it would be truly written.
I am wondering if this would be a huge Japanese script sin? Or if for artistic purposes some rules can be bent?

As much as I love and respect the Japanese language, and the text certainly means something and isn't merely a bundle of character, It is mainly for the beauty of the language rather than for the perfect grammar and punctuation.

Thank you for reading and I hope to hear your opinion

I don't know what a "script sin" is, but tattooing itself is basically considered a "sin" in Japan. I'm not saying you can't sin, though.

Tattooing katakana is not considered "artistic" nor "beautiful" in the eyes of the Japanese in general. It's usually the foreigners who chose to tattoo katakana. Most Japanese either dislike it or think "oh, well".

I hope I've answered all your questions.

I guess it will all depend on your audience. If it's for people you know and for yourself, you can tattoo whatever you wish. If you're concerned if Japanese people are going to look at it and try to correct you, they're not going to say anything. Most will probably think it's ridiculous for a foreigner to tattoo themselves in a language they don't fully understand. They may laugh to themselves, but they will never confront you with it because they probably won't care that much. After all, it's your body and you can do with it what you please. They'll just think "oh, just another gaijin!"

To answer your question, "can a dash be horizontal in a vertical text?" - I guess you mean the "long dash" to represent a long vowel. Then, no.

So you are saying, let's say you want the word "cool" in katakana. That would be　クール. And the long dash is horizontal as I am writing in horizontal text.

If we write that vertically, the correct way to write would be:

ク
ｌ
ル.

If you wrote:
ク
ー
ル
...this is simply wrong.

Whoops, sorry the "vertical" long dash in my "correct" example was not centered, though it should be.

I'm with AK, it won't look right to have it horizontal in vertical writing. Looks too much like the kanji for "one." Depending on the word, you could likely get away with dropping it all together if it is really getting in the way.

To answer your question, it would make the text illegible until you realise what has gone wrong and break out in a big smile.

By all means post a photo when it is done, very curious what one would tattoo in katakana on one's skin :-)