Guren

is a kunoichi who appears in the second Naruto Shippūden filler arc. Little is known about her yet. She is seen using what she calls and also seems to be a companion of Orochimaru. She is a character in the arc which features Orochimaru, Sasuke, the Three-Tails Jinchūriki, and the Konoha 11.

Hunt for the Three-Tails Filler Arc
To aid him in final preparations for his plan, Orochimaru sent Kabuto to fetch Guren (much to Kabuto's disapproval). Upon approaching her domain, Guren attacked Kabuto with a barrage of her deadly crystal release jutsu. Kabuto manages to evade all of her attacks and accuses her of knowing all along who he was. Guren smugly states she just wanted to make sure Kabuto was worthy of being Orochimaru's right-hand man.

Personality
Guren has shown to be a very mysterious konoichi, apparently preferring to keep to herself despite have a strong loyalty to Orochimaru. During her introduction, she quickly showed herself to be a remorseless and possibly sadistic person.

Crystal Release
Guren possesses a unique ninja art; the Crystal Release. It is unknown if this is a unique kekkai genkai or secret technique. By using this power, Guren can summon and manipulate crystal in a number of manners such as creating crushing walls or unique shurikens.

Jutsu
Guren's jutsus include Crystal Release: Crystal Prison and Crystal Release: Snowflake Shuriken. Each of them are made from the Crystal element. Both attacks are created and used solely by Guren.

Trivia

 * There have been arguments as to if Guren's Crystal Release is a sub-element similar to Haku's Ice Release and the First Hokage's Wood Release. There is also the argument that if so, that it might be a combination of earth and lightning-chakra.