I'm Banging My Rival in a Parallel World!?

Amatatsu is an ordinary, albeit brash, high school student whose life takes an unimaginable turn when he suddenly awakens in the middle of an intimate encounter with another young man. To his absolute shock, the person involved is none other than Sen, his fiercest and most persistent rival. Thrown into complete disarray, Amatatsu struggles to comprehend how such a bizarre situation could possibly be happening to him. As the initial panic subsides, a startling possibility begins to take shape. It appears that Amatatsu has been transported to a parallel world where the dynamics between him and Sen are drastically different from the reality he knows. In this unfamiliar dimension, the two rivals are not enemies at all, but rather a romantic couple. Now, Amatatsu must navigate the overwhelming confusion of this new world, reconcile his intense rivalry with their unexpected relationship, and figure out what exactly it means to be partnered with the one person he always sought to defeat.