The story deconstructs how the men view the women. Reiji put Kanako on a pedestal (the Madonna) and couldn't be sexually free with her. Seeing her act "lewd" with Kou shatters his image of her, but also awakens a twisted arousal. Conversely, Saki is viewed as the "Whore" (available sexual object), and the manga explores the tragedy of her wanting to be loved for more than her body.
This is where the "Modorenai" (Can't Go Back) part of the title becomes literal.
As of May 2026, the fuufu koukan modorenai yoru manga has been updated to Chapter 34 (Volume 7 in tankoubon format). The raw Japanese version is currently available on select platforms, while fan translations (scanlations) have reached Chapter 32-33 depending on the group.