Rin Nagumo, a skilled intelligence agent from the covert forces of Karasui, infiltrates the enemy nation of Ubataka to gather information on the powerful Minase family. His mission is clear: remain undetected, extract valuable secrets, and eliminate threats if necessary. However, within the Minase household, he encounters Shizuku, a frail girl afflicted by a terminal illness. Pure, kind, and untouched by the darkness of war, she is the complete opposite of Rin—who has long dirtied his hands for the sake of his country. At first, her presence irritates him, a painful reminder of what he has lost. But as he watches her struggle to embrace life despite her limited time, something within him begins to change. For the first time, he experiences warmth, compassion, and the desire to protect rather than destroy. Can a man bound by duty and deception find redemption in the fleeting life of a girl who has no future? A bittersweet tale of espionage, love, and fleeting hope in a world of war.