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 presumably she was shunned by others because she, like Naruto, also had unique powers. Later, Orochimaru appeared and destroyed the entire village single-handedly. He was intrigued by Guren's powers and offered for her to come with him. 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 one of Orochimaru's future vessels. When Sasuke Uchiha defected from Konohagakure and Kimimaro was no longer a suitable vessel for Orochimaru, Guren became the next best choice in Orochimaru's eyes. Unfortunately 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 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 the Crystal Release: Crystal Needles. 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 from 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. Orochimaru's decision for this sudden change is mostly unknown and appears to be a lie to use her for one last mission.

She is then sent out with Yūkimaru to go to a certain area. While this happens, Yūkimaru gets sick, forcing her to care for him. The next morning, Guren awakes to find that Yūkimaru cared for her as well by making sure she wouldn't get cold. Finally talking to Yūkimaru, she is surprised that to learn he too knows what it is like to have no one at such a young age and seems to have grown some feelings for him. She then crystallizes one of his flowers, knowing how much he likes them, so it won't wither as long as she is alive. Later when finally meeting back up with her team, she leaves Yūkimaru at the hideout while she goes out to handle the enemies, Team Kurenai. Before she leaves, she learns from Yūkimaru that he lost his mother in similar circumstance while going out to find him a red camellia. Yūkimaru also gives her his charm. While searching for the enemies, Guren comes across a red camellia patch, where she seems prompted to bring him one.

As she detects her men fighting Team Kurenai, she begins to spy on them with a crystal ball, and becomes delighted she would be facing the likes of the Copy Ninja and quickly begins preparations by summoning several crystal seeds throughout the area. After having her men fall back, she activates her seeds by shinning bright light on them, causing them to instantaneously grow into huge pillars that encase the entire area and trap Team Kurenai. There, she creates several crystal clones to fight Team Kurenai, one of which succeeds to capture and encase Hinata. Guren then uses her new hostage to warn Team Kurenai to stop following her team and her.

Then to her horror, her barrier was somehow destroyed. Quickly, Team Yamato appears and it was revealed that Naruto was responsible for destroying the barrier. Naruto and Gamatatsu try another synchro blast on her, but she easily crystallizes his attack, then using it against it by turning it into a crystal dragon. As the team then hides, Sai attacks from the sky. While doing so, and Naruto had Gamatatsu grabs the crystallized Hinata and flees along with everyone else. Annoyed at her enemies escaping, she is then greeted by her men and decides goes back to their hideout to plan their next move, but Kabuto comes in and explains another plan.

Later, Guren, Gozu, Yūkimaru and Kabuto go to sea, so that they can awaken the Three-Tailed Beast. Guren hesitates but she goes along with the plan as she still hopes to be Orochimaru's next vessel. She then joins her powers with Yūkimaru and the three-tailed beast appears. Quickly, Guren is ordered to restain the creature, where she shows herself capable of standing toe-to-toe with the mighty creature. Unfortunately, it soon becomes clear that the Three-Tails was too power. During the battle, she again showed a softer side to herself as before the fight began, she ordered Gozu to take Yukimaru away from the battle. When the Three-Tails created a powerful tidal wave that sucked her and everyone in the area in, Guren quickly went for Yukimaru and used the last of he chakra to save them. She then later awoke weakened and in Yukimaru's care.

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 like that of Kimimaro as she too was at one point a willing candidate 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. Guren is also shown to be vain by the fact that when she used her Jade Crystal Mirror technique, she looked at her self and said "Lovely, as always."

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.

Later, she then meets Yūkimaru, and thinks that he is weird. When Yūkimaru became ill, she cared for him. When she woke up, she found that Yūkimaru was outside. She then develops a sort of friendship with him as she crystallizes a beautiful flower and gently tells him that the flower will never wither as long as she is alive. This particular scene shows that Guren has a soft spot.

Crystal Release
Guren possesses a unique ninja art; the Crystal Release. It is unknown if this is a clan kekkai genkai or a unique ability exclusively to Guren. By using this power, Guren can summon and manipulate crystal in a number of manners such as creating crushing walls or unique shuriken.It is also stated by Kabuto and by Kakashi that she can crystalize moisture in the air, therefore giving her an infinite range of weapons. her crystal technique also can not be copied by Kakashi's sharingan which makes her technique unique to her only. The density of this power appears to be very high as even the Wood Release was unable to penetrate it. This ability is presumed very powerful as Orochimaru at one point desired it for himself. She can also fight and presumably defeat Kabuto with hardly any effort at all.

Taijutsu
She has taijutsu skills matching those of Kakashi Hatake, whom, in battle was having a difficult time fighting Guren with her crystalline blades.

Strategical Analysis and Diversionary Tactics
She is also skilled at scouting and observing her enemies strategies and techniques, shown when Hinata fights Guren and successfully defeats her clone. She later appears behind Hinata and binds her into a crystal. She is talented at using diversions. Shown in how she kept the rest of team 8 busy fighting her clones while she takes Hinata as hostage, and her giant labyrinth was a great diversion.

Trivia

 * There have been arguments as to if Guren's Crystal Release is a advanced-element similar to Haku's Ice Release and Hashirama Senju's and Yamato's Wood Release. This is somewhat bolstered by Guren's claim to Kakashi that the Sharingan cannot copy her Crystal techniques.
 * On the back of her coat, you can see a small white lotus flower as a reference to her name, but due to her name is different because she answered Yukimaru's question that the lotus flower was red.
 * Guren's character has similar traits to Kimimaro and Haku as both were alienated from their respective villages because of their powers and found self-worth by becoming a weapon for another.
 * Her hair style resembles the hair style of Anko Mitarashi's, as well the thirst for blood and their childhoods.
 * Her Crystal Release: Crystal Pentagonal Prison is similar to Fubuki Kakuyoku's Ice Prison Technique from the first Naruto movie.
 * Guren easily kidnapped Hinata in the Crystal Pentagonal Prison similar to Zabuza Momochi who captured Kakashi Hatake.

Quotes

 * "Hehe, I love the scent of blood."
 * "All this is starting to pump my blood."
 * "You scums are lucky to be with Orochimaru-sama!"
 * (Thinking of Yukimaru) "What, it's not like I'm going to die..."
 * (To Hinata) "Are you that anxious to die?"