There was 3 younger girls from METALVERSE.  A Offshoot of Babymetal. In this concert they flipped back and forth in some of the songs. KARATE, Doki Doki Morning were a couple that featured both. You almost didn't notice.  Yes it is one performance.

You almost didn't notice there were two babymetal for half of the song 😂

That concert with the three Metalverse girls is definitely a "spot the differences" test for reactors.

Great reaction - and you looked away from the video at the crucial moment (but even if you had been staring hard at it that may not have made any difference, it was confusing even for the people who were there).

@icipher353 has provided the best explanation in the comments below for what happened in that live performance you just watched ... yes it was all one concert, not a mash up and there was BABYMETAL and a second group of girls (a sort of alternate mini-BABYMETAL) mirroring them on a separate stage.

The two stages moved towards the centre of the arena until they met in the middle at the end of the song.

'Doki Doki Morning' was the very first song they recorded - that was October 2010 when Su was 12, Yui and Moa both 11.  The official video was made on a shoestring budget nearly a year later.

The song is about a girl waking up late and rushing to get ready for an exciting day at school with her friends.
The contrast between the instrumentals and the very cute vocals (also very apt given the song's subject matter) is very deliberate.

The guys in skeleton suits in the official video are known as Babybones.  In the early days they would go on stage with BABYMETAL to pretend to play the instruments (those were pre-recorded and played on backing track at the time).
The girls were very pleased with themselves for teaching Babybones the choreo so they could dance along with them in the video.

No, Metalverse is in the red skirts. Notice when the stage lights change to the other stage (at the break), Metalverse is from another universe. Lots of other reactors never notice at all.
You have to watch the very beginning of the opening of the show where a narrator explains it all.

People always seem a bit confused when Chibimetal/METALVERSE turn up, but I think you need a medal for that 😅

The instrumentals are heavier in their live performance than the MV's

⚡ 💀 💕 / 💓 ⏰
Some of your confusion is due to there being only three Metalverse members on stage here, but one of the comments you read mentions five people.
On stage were Miko Todaka (vocal & dance) with Sakia Kimura and Kokona Kato (both dancers).
At one point, after this show, there were two additional people performing as dancers with the group; Yume Nozaki and Miki Yagi.
The group looks like they are back down to the original three members.
Yume left Metalverse and Amuse to concentrate on her studies. Miki is focusing on her acting career, and is still an Amuse artist.
All of the members are Sakura Gakuin graduates, except for Kokona who is best known for her time in Ciao Girl, another Amuse, Inc. project.

It was one performance both groups sharing the stage(s). Not a mashup. METALVERSE are well worth checking out! While they are similar to Babymetal in looks, the sound is very different. They've released 2 Official Music Videos this year. Crazy J and Naked princess.

their is a video of a live performance of this song in 2024

Its like an anime theme 🤭🤭😅😁

Great live version with Metalverse

9:44 The guitars definitely hit harder here. I think some of the heaviness was eq'd out of the original version, due to it debuting on a Sakura Gakuin record. The drums are cleaner as well.

WIth BABYMETAL, one needs to pay close attention.  They are not BGM (Back Ground Music), so we need to have eyes glued!
I was there @ Makuhari when this happened right before my own eyes, and was blown away!

🦊🦊🦊

No wonder you are confused.
BABYMETAL will continue to amaze us🤘🦊♪

LoL...How can you not see that they are distinctly different people.

Dammmm. How you still cam understand what you see at video😂😂,BM and Metalverse performing together at the same time just different stage side by side😂.

I'm glad you finally figured it out 😂

The three girls who suddenly appeared are cute juniors for BABYMETAL in the same office.💘