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 Crystal Release brand of jutsu.

Background
As a child, Guren came from an unknown small village where she was shunned by others because she 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. It is later revealed that she in fact killed Yukimaru's mother.

Personality
Guren has shown to be very mysterious, apparently preferring to keep to herself despite having a strong loyalty to Orochimaru. 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 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. He tells her that he lost his mother in similar circumstances while going out to find him a red camellia. Guren later comes across a red camellia patch, where she seems prompted to bring him one.

Since coming in contact with Yukimaru, Guren seems to be having conflicting emotions. While part of her still wants to be accepted by Orochimaru as his next vessel, another part of her seems unable to let go of the bond she has made with Yukimaru to the point of protecting from even Orochimaru's right-hand man in Kabuto. The emotions seemed to have gotten more confusing for her when confronting Naruto, who stated bluntly how horrible and selfish a man Orochimaru really is.

After a realizing the truth about her past being connected to Yukimaru's, Guren has found herself more compelled to be there for Yukimaru then ever, possibly even a surrogated mother-like.

Three-Tails Arrival arc
To aid him in final preparations for his plan, Orochimaru sends Kabuto to fetch Guren (much to Kabuto's disapproval). Guren attacks him when he approaches her domain, but he is able to avoid her attacks. When asked why she attacked him, Guren states that she just wanted to make sure Kabuto was worthy of being Orochimaru's right-hand man. Upon returning to Orochimaru's hideout, she has hundreds of Orochimaru's prisoners fight to the death and forms a team with the survivors: Rinji, Gozu, Kigiri, Kihō and Nurari.

Guren, disapproving of Sasuke's status as Orochimaru's next vessel, is later offered a chance to replace Sasuke if she can prove herself. She and Yūkimaru are sent to a certain area. While there, Yūkimaru gets sick, forcing Guren to care for him. When he recovers, she is surprised 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 Team Guren, she leaves Yūkimaru at the hideout while she goes out to handle the Team Kurenai.

While her men fight Team Kurenai and Kakashi, Guren prepares for their arrival. Once done she has her men fall back, drawing the Konoha ninja into a trap and allowing Guren to encase Hinata in crystal. She uses Hinata as a hostage to prevent her men from being followed. Before anything can be done, Team Yamato arrives and breaks through her traps and defenses and subsequently frees Hinata. Annoyed at her enemies escaping, she decides goes back to their hideout to plan their next move, but Kabuto comes in and explains another plan.

Kabuto, Guren, and her men go out to the lake so that they can awaken the Three-Tailed Beast. When it appears she tries to restrain it, but proves no match for its strength, the whole time holding Yukimaru in a protective hug. When she uses the last of her chakra to save Yūkimaru and the others, she later awakens to find herself in the care of Yukimaru.

Guren then finds herself having a dream about the her childhood with Orochimaru and dreams about a woman. After she awakes, she finds that Yukimaru is sick again, speculating that it was because of Kabuto's overdose of pills. While taking care of Yukimaru, she detects Naruto coming and intercepts him. After a short scuffle, Yukimaru appears to stop the fight. It is here that Guren hears another view of Orochimaru from Naruto, making her question the path she has taken.

After escaping with Yukimaru, she and her team begins preparing for the final confrontation with the Leaf Village and hoping to face Naruto again to settle things with him. Upon facing the Leaf Ninja again, her Crystal Release again proves to be very powerful. Unfortunately for her, Shino's insects finally build up a strong enough resistance to make her powers useless. Although nearly perishing against her opponents, Gozu sacrifices himself to allow her to escape.

While returning to the hideout, she hears Yukimaru play with a grasswhistle and perform a melody she remembers. She then realizes to her horror that it was her who killed Yukimaru's mother. Upon the revelation, Guren begged Kabuto to not put Yukimaru through anymore pain, instead offering her own services to stop the Leaf Ninja from sealing away the Three-Tails. With the help of Rinji, Guren was able to stop the seal. Unfortunately, the Three-Tails then turned its attention to Guren. Luckily, Yukimaru was able to save her by using his powers to stop the Three-Tails.

After seeing how desperate Yukimaru was to protect her, Guren's guilt towards the boy became greater than ever, knowing that the boy was clinging to the person who had killed his mother. Deciding to atone for her crimes to Yukimaru, Guren chose to do everything in her power to protect him. Despite being battle-worn and low on chakra, Guren attacked the Three-Tails head-on. Fortunately, Naruto soon appeared the and the two grudgingly worked together to battle the beast. Ultimately, the Three-Tails managed to capture and swallow the two whole.

Inside the beast, Guren is surprised to see Naruto there as well, and even more surprised that Naruto without hesistation treated her wounds. The two quickly begin arguing about where Yukimaru belongs. Guren states bluntly that she refused to let Yukimaru succumb to any harm and that the Leaf Village is only interesting in obtaining more demons to create more Jinchūriki, apparently aware that the Hidden Village already owns the host for the Nine-Tailed Fox. Naruto stops her train of thought by revealing that he is that very Jinchūriki. Upon learning that Naruto refuses to use his demon powers in fear of hurting his loved ones, she begins to see that Naruto genuinly is concerned for Yukimaru's well-being. Together, the two begin looking for a way out of the Three-Tails.

Abilities
Guren possesses a unique ninja art; the Crystal Release. It is not clear that it is a kekkei genkai or a power unique to her, also Guren made it clear to Kakashi that he cannot copy her techniques with the Sharingan. By using this power, Guren can summon and manipulate crystal in a number of ways such as creating crushing walls or unique shuriken. It is stated by Kabuto and by Kakashi that she can crystallize moisture in the air, therefore giving her an infinite source of weapons. 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.

In addition, like Might Guy and Rock Lee, Guren has also demonstrated in times of critical desperation the ability to unlock multiple chakra gates to momentarily become rejuvenated to use her crystal jutsu at an even high level. Perhaps thanks to her crystal release, she is able to unlock certain chakra gates of her.

Guren's taijutsu skills are also rather high as she was able to fight on even grounds with an expert like Kakashi, dodge multiple Rasengan attacks from Naruto, and fight Lee and Tenten simultaneously. She is talented at noticing weaknesses in her opponent and using diversions, shown in how she kept the rest of Team 8 busy fighting her clones while she takes Hinata as hostage. After that she is seen to tell Naruto what she feels about Yukimaru. In addition, Guren also has good senses. She can easily tell when something or someone is coming.

Trivia

 * On the back of her coat is a small white lotus flower as a reference to her name.
 * To date, Guren has shown the most techniques of all filler characters.
 * She has shown to be able to use one handed seals similar to Haku.
 * Guren's Crystal Element seems to be closely related to the Earth and Wind Element seeing as how it was vulnerable to Kakashi's Lightning Blade and Tenten's flame-enveloped Weapon

Quotes

 * "Hehe, I love the scent of blood."
 * "You scums are lucky to be with Orochimaru-sama!"
 * "Yukimaru!"
 * "A short time... Just a short while...  Change my life into chakra...  Chakra Points!  Life and Death!"