Honestly surprised this is the first instances of Mario horror media on this site, especially considering the likes of MX and Mario: the Music Box's popularity.
There's a collaboration event going on between the "Toaru Imaginary Fest" game and the "Magic High School" universe. https://x.com/index_if_PR/status/1823646241764605960 It looks like Miyuki is dressed like Misaki, but she uses mostly ice attacks.
I'm guessing the monster that they're fighting is this universe's equivalent to Zelganoid, the corrupted man-made Ultraman from the 3-part finale of Ultraman Dyna?