In her everyday life, Yuuna Yuuki is a hero. As proof, she is in her middle school's Hero Club, where she does her best to help others and bring a smile to everyone's face. But Yuuna, always up to any task, is about to become an even bigger hero. Mysterious destructive forces called Vertexes begin threatening the world she loves, and the Hero Club is called upon by a strange phone app to save it. Along with her best friend Mimori Tougou, as well as sisters Fuu and Itsuki Inubouzaki, they must transform into magical girls in order to battle the Vertexes. In between studying and putting on shows for kids, Yuuna and the Hero Club must fight for the very existence of their world and face the harsh truths behind their own powers, all the while discovering what it truly means to be a hero.

Six months ago, Lord Hugh Anthony Disward, also known as Huey, lost his eccentric grandfather, Sir Wesley Disward, who was a renowned collector of rare books. His grandfather's will states that, in order to inherit his manor and everything inside it, he must take guardianship over the Bibliotheca Mystica de Dantalian—an archive that contains forbidden knowledge—and also take care of a mysterious girl called Dalian. As Huey settles into the manor, an old rival of his grandfather's arranges a meeting with him. Dalian, knowing the rival to be Wesley's killer, tags along and discovers that the murderer is in possession of a Phantom Book—a cursed tome that Wesley tried to seal away. When the book puts the two in danger, Huey discovers that the Bibliotheca Mystica de Dantalian and Dalian are one and the same, and she entrusts Huey with the key to unlocking the knowledge stored within her. Together, Dalian and Huey seal the book away, and thus begins an unlikely partnership as they solve mysteries caused by other Phantom Books.

In the newly formed Shiniki district of Tokyo, Zen Seizaki is a diligent public prosecutor at the Tokyo District Public Prosecutors Office. Assigned to a case involving false advertisement, Zen—along with his assistant officer, Atsuhiko Fumio—investigate Japan Supiri, a pharmaceutical company that had provided fabricated clinical research on the company's new drug. While investigating the file of Shin Inaba, an anesthesiologist connected to the crime, the case takes a dark turn when Zen finds a page stained with a mixture of blood, hair and skin, along with the letter F scribbled all across the sheet. As he investigates further, the case goes beyond Zen's imagination and becomes vastly complex, challenging his sense of justice and his knowledge of the truth. Digging deeper into the investigation, Zen begins to uncover a concealed plot behind the ongoing mayoral election and ties to many people of interest involved in the election and those closer than he thinks. The case grows more severe and propels Zen into an unforeseen hurricane of corruption and deceit behind the election, the establishment of the Shiniki district, and the mysterious woman associated with it all.

Katakura Kippei is in every way a high school playboy. Spending his days flirting with any girl he can see, responsibility is the last thing on his mind. Life takes an unexpected turn for him as one day he returns home to find himself with the full-time task of caring for his 5-year-old cousin. Kippei's aunt Miyako had disappeared, appearing to have abandoned his cousin, Yuzuyu. With Kippei's lack of responsibility and knowledge of childcare and Yuzuyu's injured heart with the disappearance of her mother, their time together is in for a bumpy ride.