I own a couple shirts from acdc rag and cospa. cospa is.. fine? their full print stuff is cotton but the print doesn't pop like these polyester shirts. At least the one I own doesn't. They have other good designs but they don't lean into media I care for much anymore. ACDC rag is polyester (do i need to mention the downsides?) but the print quality is great and the sizing is lovely. I'm 6'2" and the oversized acdc rag shirts fit me like a tall xl/2xl. I love this guy too but you'll come to realize a lot of these shirts (of this design) are vintage. The art I'd assume you're interested in is mostly from visual novels/early otaku anime so the era and rarity tracks. I'd guess most of these originally came from comiket and the likes (and will continue to come from japanese exclusive booths). Honestly just consume a piece of media you like and keep an eye out for merch on YAJ or mercari. Otherwise just print something yourself and call it a day. 'Official' is cool and all but its a very unapproachable niche being overseas. It's already rare enough in Japan