While many believe it's uncommon for shojo series to tackle mature issues with well-developed realistic characters, Ai Yazawa’s NANA toes the line between shojo and josei, standing out as one of the few series that manage to present its readers and viewers with a serious and mature topic. Since it won the Shogakukan Manga Award in 2002, NANA has lost nothing from its popularity -- in fact, over a decade later, it still holds up.The allure of NANA lies in its realistic yet enchanting…