I got my first pair of glasses when I was in 6th grade. Completely innocuous on the shelf, my pair of choice had light blue frames, rounded triangular lenses, and a polycarbonate coating to prevent scratching and chipping. When they arrived, all shiny and new, I innocently put them on without even thinking about the consequences. However, as soon as those baby blue frames settled on my face, a drastic transformation took place. My hair became rattier, my skin became mottled, my face broke out, and a group of boys running by yelled "HEY THERE FOUR EYES!" at me. Mortified, I quickly snatched off my glasses...and watched as my hair smoothed out, my skin cleared up, and the group of boys immediately changed directions and asked if they could take me roller skating. "Ahhh," I thought to myself as I fended off my new-found suitors, "so THIS is the transforming power of removing your glasses."
Obviously, the above story is a load of shenani-bull-crap, but I made it up to demonstrate a common plot point in many many MANY mangas I have read: the transformation that the main female character undergoes when she removes her glasses. For some inexplicable reason, the accessory of glasses does much to dissuade the attentions of other people, either platonic or amorous in nature. Those two pieces of concave glass do much damage indeed to one's social calendar, for the bearer of such unfortunate but necessary evils is regarded as an uninteresting, socially inept, total freak-o nerd girl, not worth the attention of anyone in her school, and certainly not worth the attention of the most handsome boy in the school.