Ittsuu

Sagami was dragged into sneaking into the high school that he and his two other friends were attempting to be accepted into after they graduate from middle school. While sneaking around, observing the high school girls, Sagami noticed one girl that stood out. It was love at first sight. He took a picture of her with his cell, and now uses it as his "reward" for studying harder to get into the high school. Due to this "reward" system, he successfully got accepted into the high school where the girl of his dreams attends. Now, an odd and awkward high school love life begins for Sagami.

(Source: MangaHelpers)