@pikipupiba I think your trick will be to find the right girl (most likely outside of the specific martial arts interest you have right now) and then also get her interested in that. As @Simone_De_Beauvoir suggests, you are needlessly restricting your search criteria right now by looking for the girl who is “already” interested in that activity. Out of the entire population of “people interested in martial arts who get into it beyond a ‘movement’ thing—that is, who are into the ‘hitting’ part”, how many of them are female? It seems to be a vanishingly small population.
So you’d be more apt to be the kind of person who has enough other interests and qualities as to attract a fair number of potential partners, and then convince one of that population to join you in the activity that means so much to you.
If that’s not already clear enough: Although a large number of women like sailing, and it really wouldn’t be hard for me to hang around marinas and find “a willing partner”, I select a partner that I really like from the “general population” and suggest, “Have you ever been sailing? Let’s go.” Every woman I’ve taken sailing has enjoyed it (part of the trick to that is not to take someone out for their first sailboat excursion on a ‘survival’ day, but a nice warm Saturday with gentle breezes and decent sun, etc.)
I suspect that your task is going to be more difficult than mine, because, face it, a lot more women like sailing because there isn’t any hitting! It can be physical and strenuous, but it’s not often bruising.
But if you’re the right guy, and she’s the right girl—or is so into you that a few ‘friendly’ bruises won’t turn her off—then you’ll have more luck this way.