Tennen Bitter Chocolate
Summary
From MegKF: Despite repeated rejections, Shinatsu fell in love at first sight with the most popular boy in school, Yoshiyuki-sempai (a member of the tennis club). After unhesitatingly joining the team, she gets rejected by her sempai. On top of that, she is bullied by his girlfriend. However, as her childhood friend Iku, says, "Things that are too easy to obtain aren't amusing at all." Right?