Rengoku didn't have a tragic backstory that excused villainy. He was purely good. His death is the first major loss in Demon Slayer that feels unfair. Fans search for his death scene to feel that catharsis again—but sharper.
—became a mantra for the series' protagonists, Tanjiro, Zenitsu, and Inosuke. What is "Twixtor 4K"? In the anime editing community (AMVs), is a popular plugin by RE:Vision Effects used to intelligently slow down or speed up footage.
Most top editors get away with it because Twixtor significantly alters the visual appearance of the original frames.