I just love the dynamic between these two. Hino usually starts out talking as if she’s all-in for perverse lewdness, then when Koguma (seemly) reluctantly goes in that direction, Hino yanks her chain by reminding her of a “normal” perspective on what they’re doing. Hino’s not trying to lure Koguma into yuri debauchery—I think she’s just a blush fetishist.
My guess for Hino’s request (as someone previously mentioned): wear the dress Hino made.