"Sekirei" is a manga series set in a futuristic version of Tokyo, where a mysterious organization known as MBI conducts a secret competition called the Sekirei Plan. The story revolves around Minato Sahashi, a young man who has failed his college entrance exams twice and struggles with self-confidence. His life takes a dramatic turn when he encounters Musubi, a Sekirei—a humanoid being with extraordinary powers. Sekirei are genetically engineered to bond with humans, known as Ashikabi, who can activate their latent abilities. Minato inadvertently becomes Musubi's Ashikabi, marking the beginning of his involvement in the Sekirei Plan.

The Sekirei Plan is a battle royale-style competition where Ashikabi and their Sekirei fight to be the last pair standing. The ultimate goal is to determine the strongest Sekirei, who will ascend to become the "Single Number." As Minato and Musubi navigate the dangerous competition, they encounter other Ashikabi and Sekirei, forming alliances and rivalries. Among the notable characters are Matsu, a tech-savvy Sekirei who becomes Minato's second partner, and Tsukiumi, a water-manipulating Sekirei who initially opposes Minato but later joins his group.

The narrative explores themes of loyalty, love, and survival as Minato's group grows, with each Sekirei bringing unique abilities and personalities. The series delves into the backstories of the Sekirei, revealing their origins and the ethical dilemmas surrounding their creation. MBI's enigmatic leader, Takami Sahashi, who is revealed to be Minato's mother, plays a pivotal role in the unfolding events, adding layers of intrigue and familial tension.

As the competition intensifies, Minato and his Sekirei face increasingly formidable opponents, including the Disciplinary Squad, a group of powerful Sekirei tasked with maintaining order. The story balances action-packed battles with moments of emotional depth, particularly in the evolving relationships between Minato and his Sekirei. The series concludes with the resolution of the Sekirei Plan, addressing the fates of the characters and the broader implications of the competition.

The manga blends elements of science fiction, romance, and action, creating a narrative that is both engaging and character-driven. The interplay between the Ashikabi and their Sekirei, coupled with the high-stakes battles, forms the core of the story, making it a compelling read for fans of the genre.