A book-loving girl named Ferushiana is saved from falling down a flight of stairs by a young man she does not immediately recognize. He turns out to be Yuto Historia, the eldest son of a prominent noble family, whom she last met years ago when they were both children. Not long after, Yuto proposes marriage to her, catching her by surprise. Although the reason for his sudden proposal is a mystery, she accepts. As they begin to spend time together as an engaged couple, Ferushiana finds herself increasingly charmed by the cool and capable Yuto, who has grown into a highly skilled administrative official. Yet she senses that he is hiding something beneath his composed exterior.

The truth is that Ferushiana is living inside the world of a video game titled Utopia, and Yuto is a reincarnated person who retains his memories of a previous life. In that past life, he was already deeply in love with her, and after being reborn into this game world, he has devoted himself to securing a happy ending where they end up together. Using his knowledge of the game's story and mechanics, he secretly orchestrates events to guide their relationship toward mutual love, though his single-minded devotion makes him both earnest and awkward in his efforts.

Over the course of the story, Ferushiana begins to recognize her own growing feelings for Yuto, while he struggles with the tension of keeping his true nature hidden. Matters come to a head when Ferushiana fears that their engagement might be broken off. In the climactic moment, Yuto must confess the truth of his circumstances and confront the painful distance that his secrets have created between them. The story explores the intersection of past and present affection, the loneliness of carrying a secret across two lives, and the determination to win the heart of someone who does not yet know the depth of your love.