Sattva Descreen:
http://www.descreen.net/eng/soft/descreen/descreen.htm
This is the examples:
http://www.descreen.net/eng/soft/descreen/descreen_examples.htm

The only disadvantage is that it costs 15 dollars, and may be unable to be cracked.

Tried the trial version, looks pretty good (you need to scan at least 600dpi to make it be able to detect the moiré patterns);

Using Fourier transform to denoise is nothing new, though, so I think lots of commercial denoise plugins probably should be able to get similar results.

I'd say it's more useful for real-world photo scans, for anime-style arts you generally can and will use some more aggressive filters anyway.

Some comparisons

raw (600dpi)
https://files.catbox.moe/azpbg8.png
descreened by the plugin (automatic)
https://files.catbox.moe/j4cecn.png
descreen+USM by the Epson software at scanning for comparison
https://files.catbox.moe/ilbud5.png

*shrug* Still using greystoration.

On the examples the final pics look a bit blurred, maybe that's all it does?. I'd try applying some blur until the halftone is gone then sharpen the pics back up a bit. Create an action out of it in PS, and voila, there you have your free halftone remover.