Miku, take this.

...? Mafuyu, what is this pouch...?

That's called a 'hand warmer', when it gets cold...

Yeah, yeah! I was the one who brought these!!

Look, if I do this...

Hmmm...

While I shake this, if I put my strongest feelings into it...?

! T-This has gotten so warm...!

It really has... How?

Mizuki-chan, this is amazing!

How did you do this?

That's a secret ♪

...Miku and the others looks so pleased, I guess it's fine then...

They properly explained how it works afterwards.