At London's O2 Arena, Babymetal are no longer just breaking boundaries - they're creating entirely new ones

Since then, they’ve collaborated with rock legends such as Rage Against The Machine’s Tom Morello and Bring Me The Horizon, as well as becoming regulars at the fiercely tribal Download Festival. However, the Japanese trio never played things safe to fit in with the tradition of heavy music, helping open the door for genre-blurring “pop metal” acts such as Sleep Token and Spiritbox.

Tonight’s sold-out show at London’s O2 Arena is a celebration of the past 15 years of Babymetal, but also sees the band set up their next era – one they say will “usher in a new era of heavy metal, beyond heavy metal”.

And what better way to start than Bambie Thug? Following their brilliant showing at last year’s Eurovision, their Ouija pop has been finding its way to more and more people. Snarling revenge anthem ‘Hex So Heavy’ and the chirping rave of ‘Last Summer (I Know What You Did)’ sound phenomenal in an arena, while ‘Careless’ is a tender break from the hectic, EDM fuelled breakdowns. Politically charged new song ‘REDRUM RAVE’’ is heaps of cathartic fun. Backed by the Trans Pride and Palestinian flags, Bambie explains that it’s a song for rebellion and encourages the crowd to “use their voice” whenever they can. Bambie has certainly found theirs.

Despite having just thirty minutes, Poppy’s theatrical set is a four-part existential experience that wrestles with anxiety, image and perception. It means tracks like ‘I Disagree’ and ‘Have You Had Enough’ feel even more charged, while the closing hammer of ‘New Way Out’ follows a speech about living in the moment and embracing life’s flaws. After years of zig-zagging between styles, it’s a wonderfully cohesive showcase of the world she’s built.

Before they take to the stage, Babymetal’s pre-show playlist turns The O2 Arena into the biggest metal party going, thanks to heavy karaoke anthems by System Of A Down, Linkin Park and Papa Roach. That energy continues through the opening cheerleader doom of ‘Babymetal Death’ and the sugary snarl of ‘Megitsune’, as Babymetal confidently stand alongside scene icons.

Wanting to push the genre of Babymetal even further, tonight’s set features six tracks from upcoming album ‘Forth’. Poppy joins them onstage for the nu-metal groove of ‘From Me To U’, the gorgeous, sci-fi pop of ‘Sunset Kiss’ is a rare moment of tranquillity in a bonkers set that’s peppered with flames, fireworks and confetti while the Indian folk metal of ‘Kon! Kon!’ has members of Bloodywood performing via the giant video screen. Babymetal gigs have always been over the top, thanks to clashing genres, energetic dancing and the ongoing lore around the Fox God. Tonight takes things to brilliantly odd new heights.

Even at their most playful (‘Gimme Chocolate’, ‘Headbangeeerrrrr!!!!!’ ‘Ratatata’), Babymetal’s Kami Band sounds vicious. The trio of Su, Momo and Moametal spend the 90-minute set charging between the two stages and throwing themselves into polished choreography while also taking the time to soak up how monumental this all feels. It’s the same for the feral crowd, who giddily switch from cute dance routines to churning circle pits and back again.

After a rare outing of ‘Ijime, Dame, Zettai’ (a song about the communal power of music) and the searing ‘Road To Resistance’, Su-metal thanks them for their “continued faith in Babymetal”. Well, with a show this electric, how could you not believe in their deliciously overblown vision for heavy metal?