The year is 2006 and life in Tokyo is not easy for women where they are constantly under the fear of violence. A daughter and 3 sons are raised by the Kozukis, who are both police officers. Not wanting their daughter subject to the violence of Tokyo, they raise her as a boy... The year is now 2021 and Tsukasa Kozuki is still keeping her promise not to be taken advantage of by men. Skilled in fighting, naive and honest, she's left with her three brothers when their parents die suddenly in the line of duty. Their enemy? The yakuza, a Japanese gang (mafia). The main kumi in the area was Kuryugumi, headed by a 14-year-old boy named Ryuji Shirogami whose father had just been killed. Tokyo Crazy Paradise begins with a short story where Tsukasa tries to take advantage of her enemy, the yakuza, (specifically Ryuji), a classmate who she's known since grade school. He hires her as a bodyguard to find the killer of his father. It turns out that his killer was also responsible for the deaths of her parents. Since that episode, Tsukasa, unable to pay back for the amount of food her brothers had consumed while she was putting her life in danger, she's forced to work as his bodyguard, and the story continues... and her debt increases...