^ Ok, seriously, that doesn't mean anything. It's just imagery for the PV. The first cross necklace Ayumi got was from her stylist and meant as a fashion accessory.

In all the articles I've read with "M" references, Ayumi never mentions anything significant about religious stuff and she never said that the PV was her idea (in fact, she's more likely to mention that her band was in the PV and that's what's so different about it)