Youkya ni Natta Ore no Seishun Shijou Shugi

There are two kinds of people in this world: the popular extroverts and the gloomy introverts. If you want to make the most of your limited youth, there's only one path you should choose. In other words, if you want to be popular, become an extrovert.

Kyouta Ueda, once a former introvert, reinvented himself through sheer effort and determination when he entered high school. Now, surrounded by popular kids, his school life is going smoothly. All that's left is to get himself a gal girlfriend and everything will be perfect, yet for some reason, the romantic flags keep popping up only with introverted girls...!?

(Source: Square Enix, translated)