Yugito nii

Yugito Nii (二位ユギト, Nii Yugito) was a kunoichi from Kumogakure, and the jinchūriki of the Two-Tailed Monster Cat

Backround
Yugito was made the Two-Tails' jinchūriki at the age of two and, at the end of a detestable training that was imposed on her, she was able to control her transformation into her tailed beast at will.

Personality
Yugito gained confidence in herself through hard work, making her a proud, wise, and courageous kunoichi. Also, it is said that she was firm and thoughtful of her teammates.

Abillities
The only one of her abilities ever shown in the series was the ability to turn into a smaller version of the Two-Tails, giving her an upgrade in her abilities, such as strength and the ability to breathe fire. The way she transformed is very similar to Naruto, being slowly covered in a dense blue chakra that took the form of her tailed beast. It would seem that, although she let go of her control over the Two-Tails, she still had some control over the transformation and how much of its chakra that she would use. While up against Hidan and Kakuzu she is believed to have put up a good fight, as Hidan commented before the battle that it would be hard to defeat her with the aid of her tailed beast.

According to the Second Artbook, Yugito was a highly-skilled and powerful kunoichi that even Killer Bee looks up to very much.

Hidan and Kakuzu arc
She was first seen running through the sewers from some unknown people, who were later revealed to be Hidan and Kakuzu. When she entered a large room, where all the sewers seemed to meet, she finally stopped. After some bickering between the two Akatsuki members, she revealed that she had intentionally led them there, and activated an exploding tag on the tunnel behind them, sealing them in. Knowing that they were from Akatsuki, she transformed into a miniature version of the Two-Tails. However, after 2 minutes of unseen battle, she was taken down by Hidan, and brought to the Akatsuki lair. The Two-Tails was extracted from her body, resulting in her death.

During the Five Kage Summit arc, it is indicated that Kumogakure is furious over the loss of Yugito.