Amber was an assassin trained by an anonymous underground organization in Italy. She was trained to kill and to be merciless. But then, she ran away after a mission and ended up in the Philippines. J4 is the codename given to her when she started working in JL Security and Protection Agency. Her personal information was changed and hidden. In exchange, she has only one mission: Protect the CEO of Ruby Group, Ryder Gov Gallego IV.