In a modern world ruled by the Dungeon System, Ethan Cross awakens the Legendary S-Rank Talent: [Valkyrie's Descent]. Unfortunately, the System immediately labels him "Defective" and demotes him to F-Rank for one reason: Ethan is male, and that talent is exclusive to women. However, the world doesn't know that the System hasn't locked his power. When his energy is triggered, Ethan's body completely mutates into the silver-haired goddess of war named Elysia Valerius! Now, a crazy double life begins: a bullied F-Rank male student at school, and a mysterious S-Rank female Hunter who slays monsters in the Dungeon.