Sprinkling a sugary coating of teen-idol pop on to the remorseless clamour of death metal sounds like a musical fusion best confined to the imagination of a record industry executive.
But Babymetal, a trio of Japanese teenage girls, have paired rah-rah skirts and ribbons with infernal metallic riffs to produce what could be the year's most unlikely music phenomenon.
Watch: Babymetal's song: MEGITSUNE
The band's eponymous debut album is No3 on iTunes' US rock chart and has made the online top 10 in six other countries. The video for their new single, Gimme Chocolate, has received more than 3.7 million views on YouTube, and their dramatic arrival on the international metal scene won them a place on the cover of the latest edition of Kerrang!.
Babymetal's music owes more to J-Pop perennials than to the bare-bones metal sound of, say, Slipknot. In the Gimme Chocolate video, the guitarists and drummer are practically invisible, while the catchy chorus will sound more familiar to fans of J-Pop girlband AKB48.
Babymetal - Suzuka Nakamoto, 16 and Moa Kikuchi and Yui Mizuno, both 14 - grew out of the all-girl band Sakura Gakuin. Their mission - to fuse the saccharine sound of J-Pop with thrash metal - was daunting, given none of the girls had even heard of heavy metal before they were thrown together by executives at the Amuse talent agency. But they have handled their tricky musical brief with ease.
The band's first major single, Ijime, Dame, Zettai, sold 19,000 copies in its first week, debuting at No6 in Japan.
Steve McClure, executive director of the online music site McClure Music, described "karaoke-friendly" Gimme Chocolate as "well done for what it is".
But McClure does not see Babymetal as the new face of Japan's pop industry.
"I see them more as a novelty act, and by definition that means they're probably going to be a one-off," he said.