An exceptional marksman and hopeless playboy, private eye Ryo Saeba reluctantly forms an alliance with his late partner's sister to investigate his death.

100 years ago, titans suddenly appeared on Earth. Soon, human civilization veered on collapse due to the titans. Humans then built a giant wall to defend themselves. Within the giant walls, humans lived in peace, but, 100 years later, the giant wall is broken.

Four girls take part in illegal underground fighting event "Girl's Blood" held at an abandoned school building in Roppongi every night. The girls have their own stories and quirks from their private lives. Satsuki (Yuria Haga) suffers from a gender identity disorder, Chinatsu (Asami Tada) ran away from an abusive husband, Miko (Ayame Misaki) is a S&M queen and Mayu (Rina Koike) has a Lolita face.