Set in the culturally diverse Ueno district of Tokyo, the story follows Eiko Yagami, a beautiful and dangerous detective in the Organized Crime Countermeasures Division (colloquially known as "Marubo"). Breaking all the rules, Yagami doesn't hesitate to use violence or ally with the Yakuza and the Chinese mafia. Her ultimate, driving goal is to uncover the truth behind the murder of her husband—a freelance journalist who dug too deep into the criminal underworld.