"Happy Seven" is a 12-episode anime series that blends elements of comedy, action, and supernatural themes. The story centers around seven high school girls who are chosen to become the "Happy Seven," a group tasked with protecting the world from an ancient evil. Each girl is granted a unique magical power tied to one of the seven virtues: love, wisdom, courage, justice, faith, hope, and purity. These powers are activated through special rings, which also serve as symbols of their responsibilities.

The narrative begins with the introduction of the protagonist, Nanami Kirisato, an ordinary high school student who stumbles upon one of the rings during a mysterious encounter. Upon wearing it, she is thrust into a hidden world of supernatural battles and ancient prophecies. Nanami quickly learns that she is not alone; six other girls from her school are also chosen as bearers of the rings. Together, they must learn to harness their powers and work as a team to combat the forces of darkness, led by a malevolent entity known as the Dark Lord.

The series explores the dynamics between the seven girls as they navigate their newfound roles while balancing their everyday lives. Each character embodies one of the seven virtues, and their personalities and struggles reflect these traits. For instance, Nanami, representing love, often grapples with her desire to protect her friends and maintain harmony within the group. The other members include Aoi, the calm and wise strategist; Yuki, the courageous and impulsive fighter; and Haruka, the justice-driven leader. The remaining three girls—Sakura, Rina, and Miki—round out the team with their unique strengths and vulnerabilities.

As the story progresses, the Happy Seven face increasingly dangerous adversaries, including powerful demons and corrupted humans seeking to exploit the rings' powers. The series delves into themes of friendship, sacrifice, and the moral complexities of wielding great power. The girls' journey is marked by both lighthearted moments and intense battles, creating a balance between humor and drama.

The climax of the series sees the Happy Seven confronting the Dark Lord in a final showdown, where they must combine their powers and virtues to overcome his overwhelming strength. The resolution emphasizes the importance of unity and the enduring strength of their bond, leaving the world safe—at least for the time being. "Happy Seven" concludes with the girls returning to their normal lives, though the lingering presence of the rings hints at the possibility of future challenges.