Guren

is a kunoichi who appears in the second Naruto Shippūden filler arc. She is the female leader of Orochimaru's subordinates. She uses the unique.

Background
As a young child, Guren came from a small village where presumeably she was shunned by others not unlike Naruto because of her unique powers. Later, Orochimaru appeared and destroy the entire village single-handedly. He was intrigued by Guren's powers and offered for her to come with him. In truth, Guren chose to follow him because she envied his power. Quickly, she became one of Orochimaru's most powerful and loyal subordinates. Eventually, she was offered to become Orochimaru's next vessel. But by the time she arrived, Orochimaru couldn't wait any longer and instead chose Gen'yumaru. Feeling no longer of use to Orochimaru, Guren went into isolation.

Three-Tails Arrival filler arc
To aid him in final preparations for his plan, Orochimaru sends Kabuto to fetch Guren (much to Kabuto's disapproval). Upon approaching her domain, Guren attacks Kabuto with a barrage of her deadly crystal release jutsu. Kabuto manages to evade all of her attacks and accuses her of knowing who he was all along. Guren smugly states that she just wanted to make sure Kabuto was worthy of being Orochimaru's right-hand man. Upon returning to Orochimaru's current hideout, she was put in charge of having hundreds of test subjected prisoners battle each other to the death.

Eventually after the majority of the prisoners kill each other, Guren stops the battle to make them her henchmen. When most of them decided to kill her and escape Orochimaru, Guren, without hesitation, kills them instantly with her crystal jutsu. The remaining henchmen, Rinji, Gozu, Kigiri, Kihō and Nurari, instantly decided to follow her without question.

Later, it is revealed that Guren has a deep loathing towards Sasuke Uchiha as Orochimaru values his abilities over hers and knows he will be Orochimaru's next intended vessel. She later watches Sasuke demonstrate his great power by taking down Orochimaru's army. After Sasuke leaves, Guren is shocked and overjoyed that Orochimaru has decided to give her another chance to become his next vessel if she can prove herself.

Personality
Guren has shown to be a very mysterious kunoichi, apparently preferring to keep to herself despite having a strong loyalty to Orochimaru. Her loyalty is not unlike that of Kimimaro as she too was at one point a willing canditate to become Orochimaru's next body. During her introduction, she quickly showed herself to be a remorseless and sadistic person. When told by Kabuto that several prisoners would be fighting to the death, she became ecstatic to hear there would be a slaughter.

She is devotedly loyal to Orochimaru, so much that she fell into despair when she learned she would not become Orochimaru's next vessel. It has also been shown she has a terrible relationship with Kabuto.

Abilities
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 shuriken. This ability is presumed very powerful as Orochimaru at one point desired it for himself.

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.
 * On the back of her coat, you can see a small white lotus flower as a reference to her name.
 * Guren has been a candidate as Orochimaru's new body but in the end, she didn't make it through the selection. For this she still regrets.

Quotes

 * "C'mon weaklings"
 * "Hehe, I love the scent of blood."
 * "All this is starting to pump my blood."
 * "You scum are luck to be with Orochimaru-sama!"