3 month? Kagura Games has been open since 2018, before them there's Sakura Games (who is much trashy doing localization of indie hentai games, perhaps they're the reason why Kagura Games born), and before that Nekopara already inside the steam, granted they sell R-18 patch separated outside the steam previously until Steam kinda open up for porn games.
either way it's not 3 month ago, somehow Steam has been open wide their door for like the last 3 year now, and it keep open even wider ever since big fish like Mangagamer and Shiravune get a pass.