Looked up CM as I was curious. On a japanese dictionary site, it says its "Commercial Message", but that doesn't sound right. So maybe it has no meaning? Maybe "Chick Magnet"? I don't know
@Arc hmm yeah, MC would make the most sense. It says CM in the raws too, but that's weird that such a thing would go unnoticed. In the next chapter, they'll have an MC battle, so that makes me further believe it was an error on the author's fault.