In 1999, a giant alien spaceship known as the "Heavenly Winged Ship" (Kouten) crashed in the Pacific Ocean. Inside, researchers Hiroto Minaka, Takami Sahashi, and Takehito Asama discovered 108 extraterrestrial embryos along with advanced alien technology. They founded MBI to monetize this technology and raised the Sekirei.
Minato Sahashi is not an ordinary human; he is the son of MBI's chief researcher, Takami Sahashi. He inherited a pure strain of the Ashikabi gene, allowing him to wing an unprecedented number of Sekirei (Musubi, Kusano, Tsukiumi, Matsu, Kazehana, and Homura).
The tragic "Veil" persona attacking Sekirei in Season 2 is revealed to be Uzume (#10). She is blackmailed by Eastern Ashikabi Izumi Higa, who controls the medical treatment needed to keep Uzume’s human Ashikabi, Chiho, alive. Uzume sacrifices her life in Season 2 Episode 10 to protect Musubi, begging Minato to save Chiho.
Musubi (#88) carries the dormant core/soul of Yume (#08), the original leader of MBI’s Disciplinary Squad. When Musubi's life is endangered, Yume’s divine power surges through her.
In the Season 2 climax, Minato’s flock raids MBI HQ. Matsu hacks MBI's servers, double-crossing Higa and securing Chiho's life-saving cure. Musubi defeats Karasuba (#04) using an empowered Norito. Hiroto Minaka launches himself into orbit via an escape pod, declaring from space that the Sekirei Plan will continue in a new phase. Though MBI HQ is damaged and the tournament is temporarily halted, Minato and his flock return to live peacefully at Izumo Inn.