Huh, turns out Mugensaku deleted all his works on Hentaifoundry.
He might be going "legit", which is usually the case when an artist that starts out with porn wants to stop drawing porn; this is the best case. Or maybe he is part of some website, where he is selling his porn now, which is the worst case.
Great artist too, hope to see more of his works floating around or maybe he's just under a different name.