Babymetal have really just one joke, but it’s a solid one. Since the band’s self-titled debut album in 2014, their formula has become familiar: Suzuka Nakamoto (Su-metal) sings chipper Japanese J-pop while dressed in gothy black dresses, and metalhead producer Key Kobayashi (Kobametal) provides a background of chunky death riffage and lightning-fast technical guitar solos. […]