I see both 陰キャ (Inkya) or "gloomy/introvert" and 地味子 (Jimiko) or "Rustic/Quiet/Sober girl" used for this type of girl. Basically anything with the gloomy/shy/quiet type of girl.
Some doujins
Bump. I also really like gloomy girls, like in the OP (glasses add a lot to it). I would like to see more doujins.