The story takes place in the City of Sin in a future galaxy: In order to adapt to the changes brought about by technology, a large number of galactic citizens have undergone a high degree of physical modification. However, a group of "cyborgs" has become weaponized, and a series of riots have occurred, plunging the galaxy into unprecedented turmoil. The culprit behind is a high-tech criminal organization codenamed "Illum".



In order to fight this evil force, the "Tacit Blue" investigation team led by Carl was established. They began a life-and-death confrontation with Illum, and discovered the shocking conspiracy behind the cyborg riot... During this time, each member of Tacit Blue had to face their own past and scars, and learn to face and redeem themselves, all while saving the galaxy.