There is a niche of sex work in Japan where basically models pose for photographers, and you rent time to take pictures with them. Sometimes these are former AV performers, current actresses, gravure models, and independent models.
They advertise studios where they will be availible. On Twitter, you'll see something like, "I will be at Summer Crash Salon Studio next week on these days. I hope to see you there," and guys will book time slots to take photos. Maybe nude, maybe not. Let's face it, some of them are probably doing extra services.
I suspect these models are all available at a certain studio, and someone who speaks English is taking original photos of them, and using them to run proxy OF accounts. Maybe the girls get a cut, maybe they don't. Not a bad scam when you think about it. You're basically getting to photograph pornstars you like for free. Unlike escorts, the goal is to take photos, which you can then use. I doubt these girls use Reddit or speak English, so don't know they're being used like this.