Hiruzen Sarutobi was the Third Hokage of Konohagakure, who trained under the First and Second Hokage, Hashirama and Tobirama Senju. He was the teacher of the legendary Sannin, Jiraiya, Tsunade, and Orochimaru.
Hiruzen Sarutobi was born decades before the start of the series and became the student of the First and Second Hokage of Konohagakure when he trained as a shinobi. He learned the ideals of his predecessors and, after he accompanied Tobirama Senju, the Second Hokage on a misison during the First Shinobi World War, he was appointed the Third Hokage after Tobirama decided to sacrifice himself to save his team. He went on to marry a woman named Biwako, have two sons, Asuma Sarutobi and an unknown second son who gave him a grandson named Konohamaru, train his own students, Jiriaya, Tsunade, and Orochimaru, taking special interest in Orochimaru, and lead Konohagakure during the Second Shinobi World War. During the Third Shinobi World War, Hiruzen, who had been reigning as Hokage for many years, wanted Jiraiya, his student to replace him after seeing Orochimaru, who was always Hriuzen's desired choice for the position, was not fit for it, but Jiraiya departed on a journey and left Hiruzen to pick a young man named Minato Namikaze, who turned the war in the favor of Konohagakure, to be the Fourth Hokage. At the time when Minato's wife, Kushina Uzumaki, the Nine-Tails, Kurama,'s jinchuriki was to give birth to the couple's first child, Hiruzen sent Biwako to aid in helping Kushina during the birthing of the baby, while Minato held Kurama inside her. After the Nine-Tails appeared and attacked the village, Hiruzen led his men to the village's defense and used his summon, Enma, to drive the beast out of the village. After Minato arrived to help and teleported Kurama away, Hiruzen followed and watched in shock as he saw Minato had used the Dead Demon Consuming Seal on Kurama and was present for the deaths of Minato and Kushina after they gave Naruto Uzumaki, their newborn son, their final goodbyes. Hiruzen never knew of Obito Uchiha, a masked shinobi who had set Kurama free,'s involvement in the attack on Konohagakure, but knew that the Nine-Tails didn't simply just break free on its own. Afterwards, Hiruzen resumed his reign as Hokage and began to look after Naruto, being the first person to see him as something besides a jinchuriki.
After regaining his position as active Hokage, Hiruzen began to investigate the disappearance of many shinobi from Konohagakure.and eventually found that Orochimaru was responsible for them. Hiruzen wasn't able to bring himself to kill his prized student due to his affection for him and allowed him to escape. This would later come back to haunt Hiruzen when his student made an attempt to destroy Konohagakure. When the Uchiha clan had planned a revolt against the village years later, Hiruzen made every attempt to reach a compromise with them, being the only one of the village elders to object to a massacre of the clan. After they wouldn't negotiate with him, Hiruzen relunctantly allowed the order to be given to Itachi Uchiha to wipe out the Uchiha as there was no other way to prevent the innocent from dying in a civil war, and promised to protect Sasuke Uchiha, Itachi's younger brother, from the other elders when Itachi wouldn't kill him and beseeched him to do so.
Hiruzen made his debut in series being informed of the recent pranks of Naruto Uzumaki and later told Naruto to take his school graduation photo over because it couldn't be told who it was and told Naruto never to use his Sexy Technique again after he used it in front of him. After he was informed that Naruto had stolen a scroll belonging to the First Hokage, Hiruzen ordered for Naruto to be brought to him. He located and followed Naruto with his Telescope Technique and learned that Naruto had been fooled by Mizuki, a Chunnin of Konohagakure, into stealing the scroll and commented that Kurama, Naruto's tailed beast, could get loose if Naruto tampered with the scroll after Mizuki told him the truth about his past and about being a jinchuriki. Continuing to watch as Naruto defeated Mizuki, Hiruzen called off the search for him and stated that Naruto would be back soon. After Naruto became a Gennin and started to train under Kakashi Hatake, Hiruzen assigned Naruto and his team a C-ranked mission.
After the time for the Chunnin Exams had arrived, Hiruzen first consulted the Jonin about their decision as to whether or not their students would participate in the exams and was told that all their students were ready to do so. Later, during the second phase of the exams, Hiruzen talked with Anko Mitarashi, the student of Orochimaru, Hiruzen's former student, after her former master had defeated her and heard Orochimaru's message for him. He then tried to ease the pain of her Cursed Seal of Heaven, which Orochimaru had placed on her many years before. After the second phase, Hiruzen congradulated all the survivors of the test and explained the rules for the prelimenary rounds. Hiruzen watched on as all the contestants had their turns, showing happiness and surprise at the progression of certain matches and Gennin, especially Naruto, and proceeded to announce that the finals would be held in one month to give the winners time to learn new tricks.
At the Chunnin Exams finals battle arena, Hiruzen greeted the arrival of the Fourth Kazekage(really Orochimaru in disguise) and they watched on as the finals commenced. Hiruzen was stunned when Naruto defeated Neji Hyuga, a powerful Byakugan(the strongest kekkei genkai of Konohagakure) user, with the chakra of his tailed beast, Kurama, and wondered when he learned to use it. After being advised to do so, Hiruzen put off Sasuke Uchiha's fight with Gaara until last and later gave him ten more minutes to arrive. After seeing that Sasuke had mastered Kakashi's Chidori and wounded Gaara with it, Hiruzen was impressed. However, Orochimaru then began his assault to destroy Konohagakure and forced Hiruzen into a barrier created by his bodyguards, much to his surprise and shock. After Orochimaru revealed himself, he and Hiruzen then began to battle. Orochimaru revived the First and Second Hokage, Hashirama and Tobirama Senju, and Hiruzen was brought to tears after he restored them to their living appearances. Reluctantly, Hiruzen began to battle his former masters and managed to hold his own against them at first. However, he was eventually overwhelmed by Tobirama's mastery of Water Release and Hashirama's mastery of his kekkei genkai, Wood Release, and was forced to summon his battle partner, Enma, for aid.
Engaging his revived teachers and Orochimaru, Hiruzen was again overpowered, causing Enma to question why he was hesitating. As he started to cry over seeing what the latter had become, Hiruzen managed to catch Orochimaru off guard and repel him, before blowing limbs off of his revived masters with secretly placed explosive tags. However, the damage he did instantly regenerated and Hiruzen decided to use the one weapon he had that would be effective in his current situation. At that moment, Orochimaru revealed the reason behind his eternal youth by revealing that he had mastered his Living Corpse Reincarnation technique, much to Hiruzen's intense shock. After Enma protected him from Hashirama's Wood Release attack, Hiruzen reflected on when he had last met Orochimaru and regretted letting him escape. Determined to finish Orochimaru and correct the mistake that has now brought so much suffering, Hiruzen had Enma dispel his cage.
Hiruzen then used his Shadow Clone Technique and cast the Dead Demon Consuming Seal, invoking the death god to his side. However, Hashirama(in the anime, Tobirama) used the Bringer-of-Darkness Technique to cloak the area in darkness. Hiruzen still managed to catch his former masters and allowed the death god to remove their souls as he and his teachers bid each another their final words of farewell and apology. Hiruzen then moved to seal Orochimaru too, but the latter fought back and stabbed him through the back of his chest with his Sword of Kusanagi. As he struggles to try and seal Orochimaru, Hiruzen told his former student not to underestimate the shinobi of Konohagakure multiple times and, after realizing that he was not strong enough to completely seal him, Hiruzen decided to seal Orochimaru's arms to disable his techniques and save Konoha instead. As he was nearing his end as the death god consumed his soul, Hiruzen bid Orochimaru farewell, expressing both regret that he wasn't able to take the latter with him and hope that they would one be reunited in the afterlife as master and student, and died with a smile on his face while seeing Orochimaru as a child again and knowing that the village would survive into the next generation.
In part 2, after Orochimaru had been revived, led Sasuke Uchiha, Suigetsu Hozuki, and Jugo to the Uzumaki clan's mask temple and got the death god's mask, and travelled to the Uchiha clan's Nakano Shrine, he performed a ritual which freed the souls of Hiruzen Sarutobi, along with his masters, Hashirama Senju and Tobirama Senju, and the Fourth Hokage, Minato Namikaze. Having regained his arms doing so, Orochimaru sacrificed four White Zetsu clones to revive Hiruzen and the other previous Kage so that Sasuke could learn from the ones who knew everything. Answering Hashirama's curiousity, Hiruzen explains that Orochimaru had broken the seal trapping their souls and used the Impure World Reincarnation to revive them. Shocked by this, Hiruzen wonders how this could have happened since he had sacrificed his life to take away Orochimaru arms, and yet now he had revived even him to use as a weapon against the village. Orochimaru quickly corrected Hiruzen and Tobirama by saying he revived the four of them so that Sasuke could ask them some questions. Surprised to see Sasuke with Orochimaru, Hiruzen realized he had learned the truth about his brother, Itachi Uchiha, and confirmed that everything Danzo and Obito had told him was true and that he had been protecting Sasuke after Itachi left with their trust.
As conversation between Sasuke and Hashirama progresses, Hiruzen calls out to Tobirama as he prepares to attack Sasuke and laments that Hashirama never changed when he stops his brother and begins to laughs in apology to Sasuke. After Orochimaru asks Hashirama to answer Sasuke's questions as quickly as possible, saying that hadn't much time, Hiruzen asks him what he means. Shocked to learn that Madara Uchiha had been revived and was trying to erase all shinobi in the world, Hiruzen tells Orochimaru they can talk later, asking him if he understood the seriousness of the situation if Madara was back, but Orochimaru paralyzes him and the others, refusing to allow them to leave. After Hashirama had finished telling his story and Tobirama had brought up the subject of the latter, Hiruzen states that Kagami Uchiha was the father of Shisui Uchiha, Itachi's best friend, before stating that he was the most compassionate and considerate one to inherit Hashirama's will, which made him unable to properly follow Tobirama's legacy, which caused him to rely on Danzo Shimura to do all the darker, necessary deeds that needed doing in Konohagakure, to which Sasuke tells him that he had killed Danzo. Declaring that his legacy as Hokage was riddled with mistakes and that it was his fault everything was happening like it was now, Hiruzen is comforted by Minato Namikaze, who states that he may ave been able to diffuse the Uchiha coup if he had not died too early in his reign, which Orochimaru followed by stating that appointing Minato over him was highly regarded as a mistake. After Sasuke states that he will try to save the village instead of destroy, Hiruzen consults Orochimaru, reminding him that he had said he would follow Sasuke's lead, as he and the others were still bound by the latter. Orochimaru agrees to come along and they all head outside.
Hiruzen asks Orochimaru why he is assisting Sasuke, as he had wanted to see the village perish, to which he answers that he wants to see where this new path will lead Sasuke as, unlike Kabuto Yakushi, Sasuke had not attempted to copy him. As the Hokage all jump down on their respective head carvings in the cliff, Hiruzen contemplates that it had been a while since he was in a fight, and that he he must stay focused. After Tobirama had finished warping them to the battlefield, Hiruzen, noticing Minato had beaten them there, notes to the latter that he stillslives up to his name. When the question arises as to who revived them, Hiruzen answers that Orochimaru did. After Minato activates his Nine-Tails Chakra Mode, Hiruzen asks if he has redied there positions, which is confirmed. After Hashirama rallies them, Hiruzen and the others activate the Four Red Suns Battle Encampment technique to trap the Ten-Tails. As the beast beasts prepares another of its gargantuan Tailed Beast Balls, Hiruzen, responding to Minato's obvious remark, and the other Hokage contain the enormous power of the blast, which only manages to blow out the top of the barrier. After Naruto, Sasuke, and Sakura summon their giant summons, Hiruzen, reflecting on Orochimaru, Jiraiya, and Tsunade, tells them to attack. Later, as things turn worse and Obito becomes the Ten-Tails jinchuriki and destroys their barrier, Hiruzen confronts him with Hashiram and Tobirama and agrees with the former's statement that Obito was stronger than Hashirama. After Hashirama and Tobirama's following effort fails to hurt Obito, Hiruzen, amazed that Obito didn't get a scratch, uses his Shuriken Shadow Clone Technique to attack Obito, who effortlessly counters it with an ability that Hiruzen deciphers as similar to Onoki's Dust Release. When struck through his shoulder, Hiruzen states that their was more chakra than the four chakra natures themselves combined in it, as Obito lunges forward and blasts the top of his body off and into pieces. He later reformed and arrived just in time to rescue Naruto from the Ten-Tails' final form, the Shinju, which had caught and absorbed a massive amount of Kurama's chakra, declaring that being punctual had never been his strong suit. Afterwards, Tobirama teleported both of them, and Minato to where Sasuke was.
Asserting that the Shinju seemed to be an extension of Obito that absorbs chakra, Hiruzen is greeted by Orochimaru as the latter suddenly arrives and tells him that such a pessimistic statement wasn't like him. Telling his old pupil that he was late, Hiruzen asks Orochimaru were the Kage were, being answered that they were healed and on their way, provided they hadn't lost the will to fight. Stating that Orochimaru was as blunt and harsh as ever, Hiruzen lamented it was good to see some never changed. Later, he asks Orochimaru if he means to jsut stand idly by and, after hearing his answer, tells him to lend them a hand, before the latter catches one of the Shinju's branches with his snakes, asking Hiruzen to recall the time when they were master and student as he cuts through the branch. After a Zetsu clone appears and begins fighting with hashirama's giant Buddha statue technique, Hiruzen joins the battle and directly counters all five chakra natures by using shadow clones to do the same. When Madara later activates the Infinite Tsukuyomi, a stunned Hiruzen horrifyingly asks how this could have happened, later attempting to prevent Madara's God: Nativity of a World of Trees from binding Tsunade to the Shinju after she'd fallen prey to the genjutsu, being immune to its effects himself as an non-living entity. Though he fails to save his student, he laters heads for the place where he felt the overwhelming chakra of Kaguya Otsutsuki arise, noting that it had suddenly disappeared though along the way, gathering there with the other undead Hokage and later learning the situation from a chakra incarnation of the Sage of Six Paths that emerges from the discarded lower section of Madara.
After the Sage explains his need for their help and summons the souls of many of the previous Kage to pitch in too, Hiruzen and the others work together with them under Hagoromo's instruction to teleport into and back from his mother, Kaguya's dimension with Team Seven and the dying Madara Uchiha. After listening to Hashirama and Madara breifly talk before the latter dies, Hiruzen and the other previous Kage are sent back into the afterlife by Hagoromo.
Hiruzen served as the source of wisdom for the village and always knew the correct way to handle any situation. He was also a very loving man, considering everyone in the village his family and precious to him. This was especially the case when concerning personal family and students, as he was unable to kill Orochimaru in the past, despite knowing the latter had done terrible crimes and very illegal research. Hiruzen was very honorable as well, shown when he gave his life to reverse the damage he had caused in letting Orochimaru live. He also had a sense of pervertedness to him in his youth, as he offered to help Jiraiya with his spying techniques on women, which Jiraiya made note of, and, in his old age, was usually seen with young women when not busy.
Hiruzen was one of the most powerful shinobi in history, revered as a god amoung shinobi in his prime. He was said to be the strongest Hokage and, even in his old age, he was the strongest individual member of the five Kage during Orochimaru's invasion of Konohagakure. Orochimaru himself lamened that he would not have survived his battle with Hiruzen if the latter he had been just ten years younger. In his old age, Hiruzen was able to hold his own against three Kage-level opponents with little trouble, despite being overpowered more than once. He also had excellent chakra control as, despite his dwindled chakra reserves in his old age, he was able to perform all of his techniques with a minimum amount of chakra. Hiruzen could also utilize a spying technique called the Telescope Technique, which allowed him to watch others from long distances and detects threats before they arrived. Hiruzen was called the "Professor", due to his mastery of all the techniques of Konohagakure.
Hiruzen was highly skilled in elemental techniques, able to use Earth and Fire Release very powefully individually, and was very skilled at combining them to use a stream of lava to burn through most anything. He had great taijutsu skill in his old age, able to grapple with both of his former masters after their revival easily and repel Orochimaru with just one kick. He could also use the Summoning Technique to summon Enma, a large monkey, his partner summon, who could transform into a adamantine staff as hard as a daimond at Hiruzen's command. This weapon was Hiruzen's weapon of choice, and he was very skilled at using it, able to disarm Orochimaru of his Sword of Kusanagi with no effort. He could also perform the Dead Demon Consuming Seal, which only he and the Fourth Hokage, Minato, could use. With it, he could invoke the powers of the death god and use it to seal the soul of any given target, making it his most dangerous technique of all.