The Showdown Will Be Decided by Battle Fuck [v1.0] [Let know a shop]

As he confronts the Demon King, the Hero awakens in a world that looks strikingly like his own – but here, demons rule over humanity, and the old-fashioned age of settling disputes with swords is long gone. Instead, conflicts are decided by Battle Fuck: whoever makes their opponent climax first wins, and the loser must obey.
The Hero teams up with Riina, a succubus with her own reasons for wanting to reach the Demon King’s Castle. But getting there means climbing the demon ranks—from the bottom all the way to S-Rank—by taking on the Four Heavenly Kings. Can this out-of-place Hero survive a world where even the road to the final boss is fought on its own very different terms?