Ane no Tomodachi

Hina, Asahi's older sister's best friend, is always hanging around the house he shares with his sister. She's unbelievably beautiful, irresistibly cute... and has absolutely no sense of personal space. Before he knows it, Asahi—a nerdy high school boy—is completely swept up into her antics. A gorgeous trendy girl with no concept of boundaries and a dependable, doting high school boy... They're both hopelessly in love with each other, yet neither can bring themselves to confess in this sweet, frustratingly adorable romance!

(Source: MANGA MILLION)