Bal Kress, a human Hero, confronts the Demon King in a pitch-black throne room after defeating his subordinates. The Demon King accuses humans of slaughtering Demon Race members, while Bal denounces the Demon King's invasion of human lands. They engage in a fierce battle for three hours. The Demon King activates the Great Magic [Extinction], but Bal escapes with him at the last moment, leaving the castle destroyed. Bal finds the armor empty and discovers the Demon King is a sixteen-year-old Cat Demon tribe girl named Phia, with silver hair, cat ears, and a childish face. Bal covers her with his cloak. Phia wakes up in the forest, confused. Bal explains he saved her and intends to show her the human world, believing both sides misunderstand each other. He offers her a collar to wear, so people will think she is his slave, protecting her from persecution. Phia agrees on conditions: no inappropriate touching, Bal covers her expenses, and she won't fully obey. Bal collects the ruined armor as proof of his victory.At Bal's frontline outpost, guards are shocked to see him alive. Bal introduces Phia as a child he rescued. Maid Mora helps Phia wash and dress, and Phia concocts a story that Bal saw her body and touched her after rescuing her, leading Mora to gossip. Bal returns with food and realizes Phia's prank has ruined his reputation. In response, Bal proposes they pretend to be lovers in public to control the rumor, threatening to make the rumor true otherwise. Phia reluctantly agrees after Bal covers her mouth. That night, Phia finds the human bed too hard and calls Bal over. Bal joins her in bed, telling her to lie on him. Phia uses Gravity Magic to reduce the weight and falls asleep. Bal strokes her head.The next morning, they wake up embracing. Phia panics but calms down seeing her clothes intact. Mora brings breakfast, having seen them sleeping together. Phia complains about the simple breakfast, so Bal promises to take her to the city for better food. They go to the city, where Bal gets Phia an Adventurer Card at the Adventurer's Guild. Phia uses magic to fake a birth certificate, and Bal pays the fee. They wait for the card while eating grilled meat skewers, joking around. Bal gives Phia a knife to prick her finger for the card. They leave the guild, avoiding the crowd of adventurers. Bal gets lost in the commercial district but eventually finds a dessert shop. Phia buys cakes, pancakes, and milk tea, and they return to the outpost with bags full. Mora sees them and continues gossiping. Bal's wallet suffers from the expenses. Throughout the journey, their relationship evolves from enemies to hesitant companions, with Bal learning about Phia's naivety about the human world and Phia experiencing human life firsthand. Bal aims to understand the Demon King's perspective while Phia adjusts to her new reality.
