I've seen this post on twitter today and found no entry in the site. I have to ask though, does a public post still need permission from the artist or commissioner in this case?

If it's a new artist, you should definitely ask them if they're okay with having their art here. It wouldn't hurt to ask the commissioner if they're okay with it too; while a commissioner cannot file for DNP status, they can submit takedowns.

furrin_gok said:
If it's a new artist, you should definitely ask them if they're okay with having their art here. It wouldn't hurt to ask the commissioner if they're okay with it too; while a commissioner cannot file for DNP status, they can submit takedowns.

Yeah, this, ask them if they allow their art to be uploaded elsewhere. Also always struck me as odd that E621 doesn't hold the artist as the sole person with control over what gets taken down. Except for cases with characters owned by the commissioner that is, and in those cases I'm surprised that a character can not be set as DNP.

waskom_frost said:
Except for cases with characters owned by the commissioner that is, and in those cases I'm surprised that a character can not be set as DNP.

Logistical nightmare.

Also, there is an unofficial character owner DNP list but it is not enforced for the reason above and serves just as a reminder.
With ONE notable exception because it was requested by the copyright holder of the character (look at the bear under P).

furrin_gok said:
If it's a new artist, you should definitely ask them if they're okay with having their art here. It wouldn't hurt to ask the commissioner if they're okay with it too; while a commissioner cannot file for DNP status, they can submit takedowns.

The artist already has a few posts here, but it seems spread wide so that's why I was wondering if it was due to any restriction that I'm not aware of. I also don't know japanese and I'm always afraid that google translate will inevitably fuck up horribly, XD. But anyways, thanks for the answer everyone!

haoss said:
The artist already has a few posts here, but it seems spread wide so that's why I was wondering if it was due to any restriction that I'm not aware of. I also don't know japanese and I'm always afraid that google translate will inevitably fuck up horribly, XD. But anyways, thanks for the answer everyone!

Never assume that because they have posts here, they would allow it. If you see a post here and automatically think it's alright, the next guy would think the same and the cycle continues.
Most of the takedowns here happen due to people not bothering to ask the artist for permissions in the first place (and that also includes character owners).

See topic #28775 on asking for permissions in Japanese, there are a few tips and users there that can help.