She was the world's number one genius assassin. She was ruthless and murderous, yet she was deceived and used by the organisation and met a tragic end. When she was reborn, she became a fat, stupid, useless student. Fat? She surprised everyone after losing weight! Stupid? The principal of the Taragon University personally came to recruit her! Useless? The hacker genius calls her his idol! The medical genius begged to be her minions! Even mercenaries chased after her and called her "boss"! Mathematical genius pesters for a solution! She originally wanted to experience an ordinary life but accidentally became the number one in the world. A sinister boss fell in love with her and protected her. The male and female leads always fight, yet both are obsessed with each other. The female lead is calm, powerful, and a genius who acts before speaking. The male lead is careful and loves the female lead deeply.