Detective Akira Yusa could only watch in horror as his younger brother Shinichi was ruthlessly slain before his very eyes. Amidst the chaos of the crime scene, his attention was drawn to a young woman named Kilico Sakaki who he knew with absolute certainty was the murderer. After a fierce struggle, Akira succeeded in apprehending Kilico and bringing her to justice. However, it soon became clear that Kilico was not what she seemed. Disguised as an average college student, she was actually a highly skilled assassin who had been trained by her stepfather, Toshio Sakaki. Despite her arrest, Kilico managed to erase all traces of her involvement in the crime. Determined to uncover the truth behind his brother's death, Akira launched a thorough investigation into Kilico's past. The deeper he delved, the more he realized that the situation was far beyond his control. As Kilico faced the multiple traumas of her life as an assassin, she decided to pursue a new career as a legitimate gem expert, a cover for her family's illegal operations. Meanwhile, Akira's persistent pursuit of the case eventually cost him his job. Refusing to give up, he tracked Kilico to Taiwan where their paths became entangled in the dangerous internal politics of the Tenrenban gang, the most notorious mafia syndicate in the country. As the two grew closer, they became caught up in a complex web of intrigue with potentially fatal consequences.
