If you don't want to selfhost it, there's already an instance of this running

$ git clone https://github.com/Wahyu213/Okaeri_NSFW_Detection

$ cd NSFW_Detection_API

$ pip3 install -U -r requirements.txt

$ python3 -m api

• Hentai - Hentai and pornographic drawings
• Porn - Pornographic images, sexual acts
• Drawings - Safe for work drawings (including anime)
• Neutral - Safe for work neutral images
• Sexy - Sexually explicit images, not pornography

Thanks to GantMan for their model.