Actually… I think that’s him. That bottom-left writing really reminded me of Himura’s signature on Twitter images. So I took a look at Ohmune’s Twitter account: it’s only a few days old (same for the pixiv), and judging by the first tweet it’s gonna be the account on which he’ll post R-18 stuff. Hell, even the name is a pun: “Slap in the face with big tits” (hence the avatar), and boy does Himura love ’em big.