One idea could be a story where Mash teams up with an unlikely ally from a rival school. They start off not getting along but through various challenges, they learn to work together and combine their unique skills.
Another option could be a student from a different magic school who is jealous of Mash's popularity and unique abilities. This student could use dark magic to try and bring Mash down.
Since I don't know the specific 'Muscle Magic Novel', I can't say for sure who the main characters are. But they could be bodybuilders or athletes who discover the muscle magic.
Well, without more context, it's hard to say precisely. However, it could potentially be a novel where the characters use muscle - related powers in a magical way. For example, perhaps they can transform their muscles into magical weapons or use their physical strength to perform magic that is usually associated with mental or spiritual power. Maybe it's also about a character who discovers a magical way to build muscles super - fast and then gets involved in all sorts of adventures because of this new - found ability.