Sennyu Kyodai: Tokushu Sagi Tokumei Sosakan

Kiichi is a former policer officer and his younger sister Yuki is a genius white hat hacker. Five years ago, their father Takashi, who worked as a police officer, was murdered by an unknown person in front of them. They had already lost their mother at an early age and their father Takashi raised them by himself. He was the most precious person in their lives. After their father’s death, Kiichi quit his job as a police officer and chased after his father's killer with his younger sister. But, they did not have any clues on the identity of their father's killer except that he had a phoenix tattoo on the back of his hand. Now, Kiichi and Yuki finally get into a criminal organization, which is the largest fraud group in Japan. At the top of the criminal organization is someone named Phoenix. They try to get close to this mysterious person. (Source: AsianWiki)