Kirakira No Hibi

From Moi-xRyu Scanlations:
Every morning high-school student Nanami catches sight of this one surfer he secretly begins to admire. Incidentally, however, it is later on a certain day that they reunite in a classroom! Turns out that this one-year-older senpai, named Shuu, is in fact one who, while characteristically mature, is unsociable to the extent that he’s even notorious for being someone difficult to approach. Even so, for some reason, Nanami becomes the sole person that he can smile at and laugh with, over and over again… As they repeatedly spend more time together after school, by midsummer, Nanami finds himself receiving a kiss near the seaside?! And so, a story of dazzling first love ensues.