Sekirei #88 who is the female protagonist of the series. She is the first Sekirei Minato met and made a contract with, she is also at the same time Sekirei #8 Yume, who somehow is inside of Musubi.
Musubi was one of 108 lifeforms found on Kamikura Island by Hirato Minaka in 1999 inside an technologically advance alien spaceship.
The day Minaka found them, Musubi, like all of the other sekirei after the number 8 were found in the fertilized egg stage and would eventually.
When she eventually grew up into a young child, She along with sekirei number 87 Kaho were kidnapped by an unidentified army from and unspecified country.
She would eventually be rescued by Sekirei number 8 Yume and sekirei number 4 Karasuba. Once they found Musubi and Kaho, Musubi was dying, because the soldiers that had kidnapped her, had started tampering with her Sekirei-Tama (Core) until it was all but destroyed.
Yume shed a tear for the little child and gave up the light of her Tama in order to save Musubi's life at the cost of her own, hoping that one day Musubi would meet her Ashikabi and that they would bring humans and sekirei together through the power of love.
Years later, Musubi made it her personal mission to made Yume's dream come true and she made a promise to both Kaho and Karasuba to be the last ones to survive the Sekirei plan.
Musubi would eventually be let loose into the world in order to meet Minato.
Musubi is carefree, rather naive and not very modest.
Musubi's power is Fist type she is also number 88 which means she is incredibly strong. She is Minato's Ashikabi which is her lover and her savior and for her to emerge (get more powerful) she needs DNA form another human or mucosa contact (kiss) Minato. The more Sekirei that an Ashikabi has, the stronger he gets. The more that a single Sekirei kisses their Ashikabi, the powerful they can get. This will allow them to use incantation which is their most powerful move or ability. Musubi is also another Sekirei who is a former member of the Discipline Squad Yume who is number 8 she appeared once in the second season when Musubi died she stood up and stopped what was going on between all of them and then Musubi came back out and remerge or got her symbol back that is on the back of her neck that symbolizes that she is a Sekirei.