Yukino is a Celestial Spirit Mage and a member of the currently strongest guild in Fiore, Sabertooth. She is part of Sabertooth's team in the Grand Magic Games and battled against Kagura from Mermaid Heel. Yukino possesses three Celestial Keys, two gold keys - Pisces and Libra, and the thirteenth zodiac key of Ophiuchus. She is able to summon more than one Celestial Spirit at the same time.

Spoiler

After wagering her life on the battle and losing against Kagura, she was kicked out of Sabertooth as a punishment for her failure, she was later seen outside Fairy Tail's lodging.

(Source: Fairy Tail Wikia) She is also the younger sister to Angel/Sorano. (Source: Fairy Tail Wikia and Fairy tail Manga Ch 303 pg 7.)