Setsu sucks. They hoard series on their website, drip feed most content at a snail's pace, and only show up on mangadex when someone fills a hole that they themselves left open. There are several series of theirs that I used to read but they've all but abandoned them and only seem to post more when someone else threatens to jump their claim.
Also their quality is incredibly inconsistent. I understand your reluctance to pick the series up, Osis, but it would've been cool especially since sooner or later the pre-serialization content has to run out.