A number of indie developers have received requests from Valve, similar to this one cited by MangaGamer:
We've discovered pornographic depictions in your product: Kindred Spirits on the Roof. This is a violation of our rules and guidelines for content that can be distributed on the Steam platform. We won’t be able distribute the product on Steam as long as it includes pornographic depictions.
We don't yet know exactly how many games, or developers, were sent these notices, but here are a few tweets from affected developers:
We've just received some troubling news today that @steam_games has decided to pull down our titled "Mutiny!!" within 2 weeks for 'reports of pornographic content'. Now those of you who know @Lupiesoft know that we don't put that on Steam, or advertise that content on Steam.— Lupiesoft (@Lupiesoft) May 18, 2018
We have been informed that adult content in Tropical Liquor must be censored by the end of this month or the game will be removed from Steam. We are working on this issue.https://t.co/Cs3VxVARQy #steam— NEKO WORKs@OVA配信中！ (@nekopara_pr) May 18, 2018
- IMPORTANT NOTICE -— HunieDev (@HuniePotDev) May 17, 2018
I've received an e-mail from Valve stating that HuniePop violates the rules & guidelines for pornographic content on Steam and will be removed from the store unless the game is updated to remove said content.
They all seem to be aimed at games with an anime style, but obviously Valve haven't yet issued a statement, nor are they known to do so when it comes to removing games from Steam. Some titles, including A Kiss for the Petals ~Maidens of Michael~, were removed from Steam before this notice went out, and inquiries have been ignored by PC's biggest digital storefront.
We'll keep you updated as we learn more.