Whatever Rumbler. You're meant to be asking yourself how did she become this ugly (internally), if you check out the source material (charles baudelaire) you'll see it's about a slow descent into realizing the world is ugly and getting uglier. Yes you experience that through Takao (well not really, from his viewpoint it seems like the world gets better *spoiler removed*) but Nakamura is the essence of a descent into dirt. She has all the tools to become a queen bee, her attractiveness was the first thing that had me asking myself how she ended up where she was, she's just as pretty as Saeki.
Saeki does a better job that Takao in illustrating how a seed of evil can take hold and warp a person, but Nakamura is first prize, you lose a sense of perspective when she looks like a fat, loner, loser that was forced into being a social pariah. She never was, she chose this because her life got fucked up along the way.