Following the Ryunka disaster, Tokyo is left in a period of social turmoil. To make matters worse, the group of aliens directly responsible for the catastrophic event have escaped from the Space Federation and are hiding on Earth. Still sharing a body, Space Federation officer Birdy Cephon Altera, and high schooler, Tsutomu Senkawa, are tasked with capturing the fugitives and bringing them to justice. However, an unexpected crisis develops when the outlaws become targets of an unknown assassin with a vendetta. Now Birdy must deal with the chaos of everyday life and also uncover the identity of the assassin before more escapees fall victim.

While pursuing an alien fugitive, Birdy Cephon Altera—a bombastic police officer from the Space Federation—finds herself on Earth. Her target, Geega, has disguised himself as a human and assimilated into the fashion industry, so Birdy follows suit and joins a modeling agency, taking on the identity Shion Arita. Her position as a rising model has her posing for photo shoots by day and chasing intergalactic criminals by night. Meanwhile, Tsutomu Senkawa, an average high school student, explores an abandoned building with his friend, and coincidentally, Birdy has tracked down Geega to the same building. Senkawa briefly witnesses the battle before being seized as a hostage by Geega. However, Birdy, oblivious, attacks Geega and accidentally kills Senkawa. Distraught, she quickly decides to save him by integrating his consciousness into her body. Now, Birdy and Senkawa must not only cohabitate the same body, but also balance Senkawa's high school life, Shion Arita's modeling career, and Birdy's increasingly dangerous job as a Federation officer.

The girls of 765 Production Studio are eagerly preparing for the International Music Festival on Vacation Island. Coupled with an amusement park and a high-class resort, the festival promises several days of fun for everyone. That is, until their producer announces that they only have enough room for one unit to participate. In three different scenarios where everyone is split into three groups, one of the three is chosen to partake in the International Music Festival, where they are treated to a three-day vacation before starring in the festival's concert. From the moment they step off the boat until the main event, each group of girls experiences the festival in their own way, excited to take part in the highly anticipated performance.

In a world similar to the European Middle Ages, the feared yet revered Holy Knights of Britannia use immensely powerful magic to protect the region of Britannia and its kingdoms. However, a small subset of the Knights supposedly betrayed their homeland and turned their blades against their comrades in an attempt to overthrow the ruler of Liones. They were defeated by the Holy Knights, but rumors continued to persist that these legendary knights, called the Seven Deadly Sins, were still alive. Ten years later, the Holy Knights themselves staged a coup d’état, and thus became the new, tyrannical rulers of the Kingdom of Liones. Based on the best-selling manga series of the same name, Nanatsu no Taizai follows the adventures of Elizabeth, the third princess of the Kingdom of Liones, and her search for the Seven Deadly Sins. With their help, she endeavors to not only take back her kingdom from the Holy Knights, but to also seek justice in an unjust world.