Lamune - 01Lamune tells the story of a boy named Kenji and his childhood friend Nanami. Although, everyone seems to know that they have a relationship, neither are determined to push it anymore than close friends. The story goes through flashbacks, explaining why they are such close friends and any action doesn't seem to push them apart, but draw them closer.
Taken from http://www.animenewsnetwork.com/encyclopedia/anime.php?id=5868