When the rosario around her neck is removed (only Tsukune can remove the rosario safely, but Moka is also able, albeit with potentially fatal side-effects), the seal that keeps her true nature is released, transforming Moka into a "super-vampire". Aside from the physical changes to her body (silver hair, slit pupils and a notable increase in her bust), her inner vampiric personality also emerges.

I don't see any awesome cosplay lately, so I need to do something about this. XD