[kenshiromusou]

It's your idiosyncratic feeling.
Surely, almost everyone here thinks it's wrong too, but I don't think we have the right to say the people are idiots.
Although I think you are right about these tattoos, I have the idea your reactionary reaction isn't nothing salutary to forum's harmony - even native japanese from forum, apparently, don't give a shit.
Anyway I won't say more nothing about it. To dissuade you is harder than to preach against violence to an executioner.