do i need to buy from official jirai brands to be considred jirai?

i'm a broke college student, but ive had an interest in jirai kei for a while. not only are jfashion brands expensive, but theyre not size inclusive. im an xl in American fashion and pretty curvy as well so its hard to find jfashion in my size.

as someone whos starting out with jfashion, am i required to buy from jfashion brands or is it still considered jirai to make do with what i can thrift or find in america? ive been putting off getting into jfashion and leaning more into american subcultures for a while since they lean heavily into thrifting and diy culture, but i see a lot less of that in jfashion. are there other people wear primarily American brands or even thrifted jirai, or would this be a lost cause😭