It's 10 a.m. in Tokyo and lines of grown men are already wrapped around the Saitama Super Arena to see one of the most exciting metal act around play tonight. No, not Metallica. Not Slipknot. This is a metal band centered around three teenage girls; this is Babymetal.

Comprised of 17-year-old Suzuka "Su-metal" Nakamoto and 15-year-olds Yui "Yuimetal" Mizuno and Moa "Moametal" Kikuchi, the Japanese trio's combination of pop-music melodies and heavy-metal production have cast a spell over those at home and abroad. Since releasing their self-titled debut album last February, the band hit No. 1 on Japan's album chart as well as No. 1 on Billboard's World Albums chart. They played overseas festivals like the U.K's Sonisphere and Canada's Heavy Montreal, were invited to open dates on Lady Gaga's Artpop tour and Harry Styles even gave them a shoutout on Twitter. Mind you, they're still in school and really only get to leave the country if they're on a break. 

After performing around the world in 2014, the gals are now returning home to play a sold-out arena show for 20,000 fans in Tokyo—their biggest audience to date. As the only American outlet invited, Fuse writes down every detail of the wild, kooky and totally "kawaii" concert experience. (We also sat down for an exclusive interview with Su-metal, check it out here, and Babymetal mastermind Kobametal, read that here.)

Fans begin lining up early in the morning to start buying merch. Unlike audiences in the U.S., Japanese ticket holders are allowed to buy only one item of merch at a time—if they want another item, they have to get back in line and wait again. Merch is expensive and the rigorous rules stem from problems where buyers would sell off loads of the exclusive merchandise. Thus, the early merch lineup. Everyone needs an adequate amount of time to load up on goods that include everything from Babymetal CDs and T-shirts to glowsticks and towels.

Because metal fans love some good mysticism to accompany their band history, the legend behind Babymetal is that the girls were put together by "the Fox God," and they don't come to life until summoned onstage. 

In real life, the girls do actually exist backstage. But the group goes unseen until they prance out for a select number of press interviews, wearing gothy (but cute) red-and-black dresses with perfectly styled bangs and pigtail curls. They answer many questions about their future with the phrase, "Only the Fox God knows!"

Minutes before showtime, the venue is filled...with almost all dudes. The show is roughly 70 to 80 percent guys who who love pop music (i.e. cute girl groups)—a striking difference from the slew of metal bros at Babymetal's debut New York City performance. The concert starts at an early 6pm, since child-labor laws dictate that the singers (who are minors, don't forget) need to stop working by 8pm.

The stage is set up like a spectacular castle, complete with columns, stained glass and a drawbridge that extends over the audience. This might be a metal show, but it's definitely got the feel of an over-the-top pop production a la Gaga or Katy Perry

After a dramatic introduction video where the members emerge from coffins, the trio hit the stage showcasing big-diva belts from Su-metal, whose title is vocalist/dancer, over Slayer-like backing as Moametal and Yuimetal adorably shout song hooks. Their performance includes non-stop choreography, but it's at times toned down for the audience to join in. If Babymetal jumps, thousands of men do the same. If Babymetal raise their hands together, the audience follows too. The end of every song is met with the kind of husky hurrah you hear at a football game—a big difference from the screaming teens Western pop fans might be used to filling arenas.

Watch Babymetal perform "Headbanger":

The show continues with loads of highly technical production. Neon laser lights fill the arena during the song "Iine!!" making you feel like you're inside a space-age video game. Later, fireballs spark across the stage. 

Meanwhile, Babymetal's backing band is freaky looking (with white cloaks, white face paint and dark black paint over their eyes), but also freakishly talented. The show features multiple opportunities for the guitarists, bassist and drummer to shred in the solo spotlight. 

The girls also perform two new songs. The first is an unreleased track that fans have tentatively dubbed "Bubble Dreamer" before its official release. It boasts a baby-talk hook by Moa and Yui with an addictive pop chorus by Su that recalls the melody from Katy Perry and Timbaland's "If We Ever Meet Again." The group then closes out the show with "Road of Resistance," a collaboration with power-metal veterans Dragonforce that brings speed metal to a place it's never previously been. 

The girls have little audience interaction throughout the show, save for the occasional shout-outs of "Babymetal in the house!" and "Are you ready?!" But the big smiles and waves the trio send the sea of supporters, even after two hours of nearly non-stop choreography, proves to be more than enough. The massive audience also leaves in smiles, seemingly amped to support wherever Babymetal take their kawaii metal in 2015.