trying to find a hentai manga. a woman is being blackmailed by a guy, or maybe needs money for him or something. he somehow captures her, i think the envelopr with the thing she needed was on a trapdoor over a pit, and she's forced to climb a wall of dildos to get out (not pic related, just the closest thing my searching finds). later she's forced to walk along a bar pressed to her crotch with a series of grooves to stimulate her. think it ends with the typical 'haha i have now made you my sex slave' stuff.