Saishuu Heiki Kanojo

The protagonist of the story is Shuji, a student in Hokkaido. His classmate Chise has already confessed her feelings to him at the beginning of the story. However, due to Chise's shy nature and Shuji's lack of eloquence, they begin their relationship by exchanging diaries. One day, while Shuji and his friends are shopping in Sapporo, unidentified bombers launch a fierce attack on the city. While seeking cover with his friend, Shuji witnesses a small, fast-flying object attacking the enemy bombers. After becoming separated from his friend, Shuji wanders through the ruins. There, he encounters Chise, who has grown wings and weapons, no longer has a heartbeat, and wears tattered clothes. Chise tells him that she has become the Japanese Self-Defense Forces' "Ultimate Weapon," and thus the story begins... In an unnamed town in Hokkaido, amidst middle school students whose emotions are just awakening, who could have foreseen that this was the peace before the apocalypse? Shuji, handsome yet still somewhat stiff, and Chise, cute but always slow to understand things—they had only just decided to properly start their romance when they were forced to endure the torment of fate. She, transformed into the Ultimate Weapon, endures physical mutations and the pain of having to destroy in order to protect, struggling to maintain her romance with Shuji. He, witnessing her suffering yet powerless to help, constantly struggles to keep this fragile love alive. As one friend after another dies, the belief that they want to protect each other and live together tightly binds them. The two compose a love song for the end times with their true hearts. We also want to lean on each other and survive... The last sound of Earth... It sounds like Chise's heartbeat... This is the final, all-out song of this planet and us... A love song... We will continue to love each other... Survive...