The story takes place in Tokyo Butei High School, a special school where armed detectives—"Butei"—are trained to use weapons. Kinji Tooyama is a second-year-student who has a special ability, but he keeps it a secret to maintain an ordinary, peaceful life; however, when he gets caught in a bombing on the way to school, he encounters H. Aria Kanzaki, the most powerful S-Rank Butei student in Assault Studies.

Dr. Raichii is the only Tsufurujin (the race eradicated by the Saiyajin many years ago) thought to have survived. He now is going to take revenge on the only surviving Saiyajin still alive, Goku and Vegita. He uses machines that emit destron, a gas that will destroy all life on Earth. Now the the Z warriors only have 72 hours to find and destroy Dr. Raichii. (Source: ANN)

Yui is an average schoolgirl who lives in a future where all computers are supported by a single global network known as COMNET. Yui is a computer-illiterate girl who after a computer-lab accident is approached by IR, a raccoon looking corrector computer program, which tells her she must save COMNET. She must stop the rogue A.I. (Artificial Intelligence) computer program known as Grosser and his hench-programs from taking over the world. Grosser was originally designed to be that manager of all of COMNET. At first she's very reluctant to play the heroine because of her complete lack of knowledge and ability with computers. To save COMNET she must find and gain the trust of the other seven wayward corrector programs. They must also find the creator or COMNET Professor Inukai, to help stop Grosser for good.

Although cheerful and delicate, Sakura Sakurakouji is a skilled martial artist with a sense of fairness that never falters—no matter the situation. Upon witnessing people burning in blue flames while on a bus ride home, she calls the police to bring their murderer to justice only to find that no evidence remains. However, all her doubts about what she saw vanish when the next day, the new transfer student Rei Oogami joins her class; he is the very boy she watched commit murder in cold blood. Rei is kind, sweet, and quickly becomes popular, contradicting Sakura's accusations. Soon enough, she learns his true nature: a Code Breaker, or "one who does not exist." To Sakura's shock, Rei—armed with mysterious powers—seeks to exact justice according to the principle of "an eye for an eye." Determined to bring Rei to the right path, Sakura keeps close to him in the hopes of redeeming him from his ways before others are hurt. [Written by MAL Rewrite]