Summary snagged from Wikipedia:
Nanami Takahashi, a 15 year old high school student, falls in love with and begins dating the most popular guy in school, Motoharu Yano. However, their relationship is not easily maintainable. Yano's past, as well as the complex emotions they bring up, make it difficult to be completely honest about how he feels. To add more troubles to their relationship, caught in the middle are Yuri Yamamoto, the younger sister of Yano's now dead ex-girlfriend, and Masafumi Takeuchi, Yano's best friend. Yuri's past with Yano goes deeper than one might suspect and her feelings run deeper than she portrays in public. Takeuchi cherishes Yano's friendship, but at the same time, he may lose it for someone dear to him, Nana. The story revolves around how Takahashi must search deep inside herself and find her true feelings for Yano whilst being able to trust and accept Yano's feelings for her as well, deciding if Yano is indeed the one for her or if someone else can provide better solace.
Hope that photo works.