Just a little story of a samurai and a Blacksmith meeting that totally has nothing to do with Mirror War

Kiyo Yumito has a relatively normal life, until one day, a girl, who looks exactly like his childhood imaginary friend, attends his school. She is real. She always was, just not in his world.
The universe is devided in two identical paralell universes, inwhich a phenomenon occurs: certain things, in particular humans, don't exist in one world, but do in the other. This causes disruption, so the god of this world, Darkness, organizes a deathgame in her home for the anomalies to fight to the death for population control. And little does Kiyo realize how little it matters if he believes it or not...

This comic is carried over from webtoon, which has been going since May 27th 2021