Kisaragi Saya is a lonely, gloomy high school girl who is cursed to never be noticed by those around her, almost like a ghost. During her first summer in high school, Saya discovers the full-dive VRMMORPG "Shadow Assassin's World," changing her world forever. Even in the game, amidst a world monsters, demons, and other players, Saya finds that her presence is still nearly undetectable - so she decides to turn her curse into a blessing to become the top-class Ninja, "Kuro!" One day, an extroverted Ninja named "Hikari" crashes into her life and asks to be her apprentice! What lies ahead for this pair of polar opposites?