OK, I just checked Wikipedia and it turns out I was right.
From the "Kawaii metal" page:
The Japanese girl group 
Babymetal is often credited with the creation and success of kawaii metal. In addition to Babymetal, kawaii metal acts such as 
Ladybaby have garnered media attention, as well as minor commercial attention, for performing songs of this genre.
History and characteristics[edit]

Kawaii metal pioneers 
Babymetal, performing in 
The O2 Arena London in 2016.
Japanese 
heavy metal idol group 
Babymetal are considered the inventors of the kawaii metal genre.
[5][6] The concept of kawaii metal started with 
Key “Kobametal” Kobayashi, the producer behind the group Babymetal. In an interview conducted by Billboard, Kobayashi explains that he was “just trying to do something no one had heard before”.
[7] Kawaii metal gained international popularity in 2014, when the group Babymetal uploaded a song to Youtube called 
Gimme Chocolate!!. As of April 2021, the video has received over 140 million views.
[8] Angelica Wallingford of 
City Times opined that Babymetal's 
eponymous debut album had pioneered the kawaii metal musical genre. Wallingford also defined the genre, and album, as a "mixture of varying genres including 
pop, 
rock, heavy metal, 
electronic dance music, 
industrial and 
symphonic death metal".
[9] A guest contributor at 
The Independent believed that the genre was a derivative of 
J-pop and various 
extreme metal genres, namely "
speed metal, 
power metal, 
black metal, and 
industrial metal".
[10]
While discussing Babymetal, 
The Sydney Morning Herald's Rob Nash stated that the genre consisted of "sugary pop melodies over 
thrash metal". Nash also believed that the group's song "
Awadama Fever" exemplified the genre, with its "slabs of angry guitar and undanceably fast breakbeats, while the girls [Babymetal] squeak about 'bubble ball fever' and chewing gum".
[11]
Babymetal has remained extremely popular. In 2019, Babymetal became the first Asian artists to top Billboard’s Top Rock Albums chart, with their third studio album, 
Metal Galaxy.
[12] Murray Stassen in 
Music Week commented that "Babymetal is, without a doubt, a genuine cross-genre musical phenomenon" and that, despite how the juxtaposition of metal and J-pop might not seem to make sense on paper: "[Babymetal has] proved that it can, and does work, and resistance to the Babymetal phenomenon is futile."
[13]

Kawaii metal band 
Deadlift Lolita in 2017.
Discussing Ladybeard, and Ladybaby, Jake Cleland of 
The Sydney Morning Herald defined the genre as "saccharine pop with his heavy metal 
growling".
[14] Alex Weiss of 
Paper defined the genre as "
hard rock with sugary sweet pop hooks". Weiss also used Babymetal's songs "
Karate" and "
Road of Resistance" as examples to explain the differing lyrical perspective between the kawaii metal and other metal genres, stating that kawaii metal songs "offer a perspective often missing from the 
hyper-masculine, aggressive lyrics usually present in most of the [metal] genre's hits".
[15] Felix Clay of 
Cracked.com also believed that the genre had less aggressive lyricism, citing the genre had lyrics about "pop music topics like kittens, chocolate, and fun".
[1]