Megane-chan

Kogane is a socially clueless, glasses-wearing girl who works at a convenience store. She has a huge crush on her manager, Fuuta, but he doesn't seem to return her feelings at all. Luckily, Kogane has a little sister, Akane, who is much more fashion conscious and adept at social situations. Akane is determined to help her awkward big sister get the boy she wants!

(Source: MangaHelpers)