Ninja Nose Scar, Done on Purpose?

This is my second question I’ve always really pondered. I haven’t been able to find info on it, whether its because I haven’t worded it right or because there just isn’t anything to tell on it.

Yet again I’m going to refer to anime, which I know is easily changed and most often changed for it’s fan base, and in some cases movies. But this question is about the Horizontal nose scar that you see many ninja having.

I was wondering a couple different things.

-Was this something that was popularized through a person or an anime?
-If it was in fact something that was done on purpose, why?

And something that I’ve always wondered, is could a slit/scar on the nose that far up, make it possible to breath from? I know it may sound awkward, but I always thought they might have done it because the masks they wore might have been difficult to breath through.

Thanks in advance guys!

Strange. I’ve never seen or heard about anything like that, either related to real (historical) or pop-culture ninjas. Care to give an example?

Maybe its just an injury scar? Something to make the character look badass?

I’m thinking it’s the cartoon depiction of a schmiss, intended as a shorthand for “hey, this guy has spent some time having live steel swung at him.”

It’s not always the nose, and it’s just to make the character look like he’s been in fights. It’s not a ritual scar or anything.

I couldn’t say where it first started. The oldest character I can think of with an obvious facial scar is Black Jack, but that character is a doctor not a samurai. Still, I wouldn’t be particularly surprised if that is the first character to have this since it’s an Osamu Tezuka character.

Qualifications: Lived in Japan for seven years, professionally studied anime, and has read thousands of manga