**"Swear to keep this secret and pledge yourself as my eternal ‘sustenance’ from this day forth—…"** For Ruri, an overworked office worker with a frail constitution, her only solace was Gilbert, her favorite character from the otome game *Vampire’s Manor*. But one morning, after pushing herself too far, she collapsed… only to wake up in the game’s world, face-to-face with Gilbert himself! **Except, she had reincarnated as Fiona, the doomed fiancée destined to be killed by him!** Now, to avoid her grim fate *and* stay close to her beloved character, Fiona begins her desperate struggle. But before long, her motivation shifts, **from mere survival to a burning desire to save Gilbert, the man who was never truly loved in return…**