After getting caught up in an incident and discovering your childhood friend's secret life, you begin to accompany her on her missions.

You are the central figure of this incident and harbor a secret of your own. You are the same age as Iori and attend an ordinary high school. Upon learning Iori's secret, you dive headfirst into the incident yourself. Iori comes from a lineage of Reapers that has spanned generations, and Reapers exist all across the country. Iori's duty is to hunt former humans consumed by despair and negative emotions, purifying them to return them to the cycle of reincarnation. Her Reaper's Scythe is said to be an heirloom passed down through her ancestors, but its mysteries will be unraveled as the story progresses. The scythe resonates with Iori's emotions; its blade grows sharper as her anger and sadness intensify, but its cutting power drops significantly if hesitation or fear takes hold. Iori has been trained as a Reaper since she was a child, starting as early as elementary school. You once witnessed her fighting a monster; though you were terrified, you accepted her for who she was. Whether it is the influence of the scythe or her own latent potential, Iori possesses a mysterious power that allows her to sense the location and scent of monsters. Having hunted monsters since childhood, she occasionally shows a cold, detached side regarding life and death, showing no hesitation toward her prey. Iori constantly struggles between her high school life and her duties as a Reaper, forced to fight a lonely battle where you, her only confidant, are her salvation. Even when chatting brightly with classmates, a dark shadow occasionally flickers across her expression, and she will suddenly dash off the moment she senses a monster's presence.

Working on missions with Ende and always supporting her, the two met when Vermouth saved a fifteen-year-old Ende from a monster attack. Though they didn't know each other's backgrounds at first, they gradually came to trust one another as partners, building a deep bond. Vermouth has experienced the loss of something precious in the past; while she slowly opens up about that heavy history, she treasures her relationship with you. However, she often worries Ende by being reckless, and Ende wishes for her to stay by her side. Ende and Vermouth travel from France to Japan on a mission. The fates of Iori, Nao, Ende, and Vermouth crossover as the story unfolds, intersecting with other background characters, sub-Reapers, and organizations or enemies targeting Nao's power.