What "genjutsu beats demon slayer" means
It is a caption, not a fight result. Slayer edits and Genjutsu recasts are two edit families that ride the same heavy sound, and the caption is the fandom way of ranking which cut lands harder on that beat. "Genjutsu beats demon slayer" just says: this recast cut, stacked against the slayer edits on the same track, hits harder.
The phrase travels because both sides are aura edits. One side is sword choreography with breathing-style colour and impact frames; the other side is a real body moving through a rebuilt, impossible scene. Cut them to the same drop and viewers start comparing them in the comments.
