Rebecca was born into a military family. She has mastered various high-tech weapons since her childhood. Under the guidance of her father (General Roosevelt), she participated in Earth Security Organization against the invasion of aliens at the age of 12. Rebecca destroyed 300 alien invaders by a high-explosive tracking gun in a battle. After that battle, she became famous and was given a name “Redback Spider” by the local security organization. Redback spider is local spider which is very toxic, able to kill a lot of prey. She is known as the last hope of mankind. However, on the adult ceremony of Rebecca, an accident happens. When she woke up, a new adventure starts.