In a far future, after a meteor struck Japan, America and China rebuilt the country and also created a large wall to block out the contamination. 15 years later, a police officer named Rachel Kinoshita, after being assigned a case to stop a digital drug dealer known as "Skull Daniel," she receives a new partner, a bubbly Asuka Mizutani, who shows deep affection towards Rachel. Then, Rachel finds out that Asuka is actually an incredibly power and nearly indestructible android! As the two work and live together, Rachel starts to open up more to Asuka, and the two become closer and closer to finding Skull Daniel...

Double Heroine was also aired from November 2010 to September 2011 as a radio drama on Bubka Broadcasting during "Ukkari Channel" talk show hosted by AKB48's "Twin Towers," Akimoto Sayaka and Miyazawa Sae. The roles of Rachel and Asuka were made respectively based on their personalities. There was also a live musical show with the voice actors reprising their roles. Since the radio drama ended in the middle of the story after "Ukkari Channel" stopped airing, the manga is the only complete version of the story.