Based on the Japanese Manga: Koizora tells the story of Mika, living a simple school girl's life until one day, when she loses her phone in the library. It is soon discovered that her phone was recovered by a boy named Sakurai Hiroki, who first communicates with Mika through her phone, until the day they finally meet when Hiro returns Mika her phone. From then on, a friendship turned to a romantic relationship, but hardships like rape and disagreement meet the couple along the way. And then...