"Bungaku Shōjo Memoir II - Sora-Mau Tenshi no Requiem" is a sequel to the "Bungaku Shōjo" series, continuing the story of Touko Amano, a "literature girl" who consumes books as her sustenance, and her assistant, Konoha Inoue. The narrative revolves around a mysterious manuscript titled "Sora-Mau Tenshi no Requiem" (The Requiem of the Soaring Angel), which Konoha discovers in the school library. The manuscript, written by a girl named Miu Asakura, tells a haunting tale of a boy and a girl who make a pact to die together, only for the boy to survive. The story within the manuscript mirrors real-life events involving Miu and her childhood friend, Shuji, who attempted a double suicide years earlier.

As Konoha delves deeper into the manuscript, he uncovers the tragic connection between Miu and Shuji. Miu, now a reclusive and emotionally scarred individual, struggles with guilt and unresolved feelings over Shuji's survival. The manuscript serves as a cathartic outlet for her pain, blending fiction with reality. Touko, recognizing the emotional weight of the story, encourages Konoha to confront the truth behind Miu's past and help her find closure. The narrative explores themes of guilt, redemption, and the power of storytelling as a means of healing.

The main characters include Touko Amano, whose enigmatic nature and love for literature drive her to understand and empathize with others' emotional struggles. Konoha Inoue, a former novelist, serves as the bridge between Touko and the outside world, often grappling with his own insecurities and past mistakes. Miu Asakura is a central figure in the story, her tragic past and emotional turmoil forming the core of the narrative. Shuji, though not physically present, looms large as a symbol of Miu's unresolved grief and guilt.

The plot intertwines the fictional story within the manuscript with the real-life events of Miu and Shuji, creating a layered narrative that blurs the line between reality and fiction. As Konoha and Touko work to uncover the truth, they help Miu confront her past and find a path toward healing. The story concludes with a resolution that emphasizes the importance of facing one's emotions and the redemptive power of human connection.