In an abandoned warehouse, there lived a mad scientist otaku who wished for the world to be an anime. That mad scientist otaku is you. You've been bullied for liking anime as a college student, and you figured that if the whole world understood just how awesome anime is, your bullying problem would be gone. And so you invented the animification chamber. You planned to lure people in and change them as you see fit, including their anime character type, breast size, butt size, voice, etc,.
To attract the right people, as otakus and weeaboos were more likely to be changed more quickly, you disguised the warehouse as a cosplay shop. You did intend to sell costumes, but only after they had transformed. By then they'd just see it as a regular clothing store.
Today was the first day but business was slow. However someone finally arrived just before closing. But who?