“We’re goin’ up, up, up, it’s our moment,” sings Rumi, the purple-haired lead vocalist of Huntrix, a girl group, as the crowd roars. Rumi and her two bandmates star in “KPop Demon Hunters”, an animated musical film in which Huntrix battle their rivals, the Saja Boys, for higher stakes than just a spot on the pop charts. The boy-band is actually made up of demons disguised as heartthrobs who steal their fans’ souls, which the underworld’s demon king eats. Rumi’s lyrics have proven prophetic. Released on Netflix in June, “KPop Demon Hunters” has become the platform’s most-watched film ever, amassing 236m total views. Three things explain its success.