Mito Uzumaki

was the wife of Hashirama Senju and the first jinchūriki of the Nine-Tailed Demon Fox.

Background
The Uzumaki clan and the Senju clan, having a common ancestor, had always had close ties. For this reason she married Hashirama Senju, who would help found Konoha and become the First Hokage. After Hashirama defeated Madara Uchiha and gained possession of the Nine-Tails, Mito volunteered to have the beast sealed within her to help Hashirama control it. The sealing was performed with her clan's unique fūinjutsu, from which the Four Symbols Seal would be derived. Despite the seal's strength, it almost broke at some later point when Mito was going through childbirth.

Towards the end of Mito's life it was decided to find a new host for the Nine-Tails. Kushina Uzumaki, one of her kinsmen, was selected for the role due to her special chakra, and was terrified by the idea. Mito comforted her and, before the transfer was performed, told Kushina that love was the only way to tame the Nine-Tails' hatred.

Appearance
Mito was shown to have worn an elaborate kimono. Her hair was seen tied up in buns similar to Tenten and a diamond mark on her forehead, similar to that of her granddaughter Tsunade. She also has what appears to be seal tags in her hair decals.

Abilities
Not much is known about her fighting skills but Kushina said she was a powerful kunoichi. She was proficient enough with fuinjutsu to seal the Nine-Tails within her and is remarked as having incredibly potent chakra capable of restraining the beast. Due to being a member of the Uzumaki clan, Mito had an exceptionally long life.

Quotes

 * (To Kushina)