Tobirama Senju was the younger brother of Hashirama Senju, the First Hokage of Konohagakure, who suceeded his brother as Second Hokage and trained Hiruzen Sarutobi, the Third Hokage of Konohagakure, with his brother before he died.
Tobirama Senju was born into Senju clan before the era of shinobi villages and grew up alongside his brothers, Itama, Kawarama, and Hashirama Senju. Though he is younger than Hashirama, whether he is elder to Itama and Kawarama is not known. When they were kids, Kawarama was killed in a battle that the Uchiha clan, the Senju's rival clan, had taken part. At his funeral, Hashirama spoke out against their father, Butsuma Senju, who punched him, causing Tobirama to criticise him. After Hashirama continued to voice his unapproval of his father's words and beliefs, Tobirama stood between them and begged their father not to hit him again, saying Hashirama was simply overwhelmed by his emotions. Later, after the funeral, Tobirama told Hashirama and Itama that if the adults really wanted to bring an end to the constant fighting, then they should simply sit down with their enemies and work out a truce. Criticising Itama for thinking like the adults, Tobirama stated that shinobi should establish a code of conduct and stick to it to end pointless fighting. Some time later, Itama was killed by the Uchiha clan. After being sent by his father to tail Hashirama, who began to meet regularly with Madara Uchiha, Tobirama told his brother they must have a talk. Later, their father ordered Hashirama to gather intel on the Uchiha by following Madara, saying that he and Tobirama would follow him just in case. On the day of the trap, After Hashirama and Madara warned each other, Tobirama and Butsuma confronted Madara's father and brother, Tajima and Izuna Uchiha, whom Tobirama battled with evenly. After Madara's father tried to kill him, Hashirama saved Tobirama and Madara and his family fled.
Throughout the following years, from childhood to adulthood, Tobirama grew into an immensely powerful shinobi, who backed his brother as leader of the Senju clan. One day, Tobirama and Hashirama confronted Madara and Izuna Uchiha, each pair backed by some of their clansmen. Hashirama and Madara were evenly matched as always, but during their battle, Tobirama managed to fatally wound Izuna with his Fly Thunder God Slash technique. Soon after, Madara fled with Izuna, and the rest of the Uchiha present allied with the Senju, Hashirama having offered a truce. Some time later, Tobirama, Hashirama, and their clan were confronted by Madara, who had attained the Eternal Mangekyo Sharingan. After a fierce battle that lasted a full day and night, Madara was finally defeated, and Tobirama prepared to finish him, only to be stopped by Hashirama, who ordered him to back down. Hearing Madara's compromise about how Hashirama could earn back his trust, Tobirama asked him if he would kill him or himself to please Madara. Hashirama decided to kill himself and ordered Tobirama not to kill Madara, who stopped him at the second and willingly accepted the truce. The Senju, Uchiha, and all the clans they had conquered made a pact with the Land of Fire, who needed aid in controlling their territory, leading to Hashirama and Madara founding the village of Konohagakure. Tobirama opposed Hashirama's decision to make Madara the head of the village, saying they would never accept him as such and that even the Uchiha clan saw Hashirama as the true founder, unassisted by Madara, unaware that Madara was listening. Tobirama then suggested that they use democracy to decide who would become the First Hokage, to which Hashirama agreed.
Hashirama became Hokage and later stopped a vengeful Madara from destroying the village in the battle that resulted in the creation of the Valley of the End. In the following years, Tobirama and Hashirama trained the young Hiruzen Sarutobi as a shinobi and taught him the Will of Fire(their shared belief of love being crucial to peace and that a Hokage must believe in his people as much as they do him). Tobirama succeeded his elder brother as Second Hokage after his death. Once, while meeting with the Second Raikage in Kumogakure to try and formulate an alliance between their two villages, Tobirama was mortally wounded by Kumogakure's Gold and Silver Brothers, Kinkaku and Genkaku, who were attempting to stage a coup, barely managing to escape with his life. Some time later, while on a mission with Hiruzen, and the rest of his team, Tobirama decided to distract the Kinkaku Strike Force, led by his attempted assassin, and sacrifice himself to allow his teammates to escape, but not before appointing Hiruzen as the Third Hokage.
Tobirama Senju was revived alongside his elder brother, Hashirama Senju, by Orochimaru in order to give Hiruzen Sarutobi, his former master, the feeling of what it was like to fight one's former teacher. Tobirama and his brother briefly conversed with Hiruzen about their situation, before being robbed of their free will by Orochimaru and being forced to battle Hiruzen against their will. Tobirama and Hashirama managed to overwhelm Hiruzen with their immense power of Water and Wood Release, forcing him to summon his partner, Enma, for aid. However, this changed nothing as Tobirama and his brother still managed to overwhelm him with Orochimaru. Hiruzen then cast his Dead Demon Consuming Seal and summoned the death god to counter the three Kage-level opponents, but Hashirama(though it was Tobirama in the anime) cast his Bringer-of-Darkness Technique and shrouded the area in darkness. Hiruzen still managed to grab hold of the brothers and allowed the death god to reach its arm into them and grab their souls, dispelling the darkness and freeing them from Orochimaru's control. Tobirama and Hashirama then briefly conversed with Hiruzen and apologized for the trouble they had caused him as he sealed their souls into the death god's belly, along with his own.
In part 2, after Orochimaru was revived, had 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 that freed the souls of Tobirama Senju, his older brother, Hashirama Senju, their student, Hiruzen Sarutobi, and the Fourth Hokage, Minato Namikaze. Having regained his arms in doing so, Orochimaru used his Impure World Reincarnation technique to again revive Tobirama, along with the other previous Hokage so that Sasuke can learn from the ones who know everything. Recognizing Orochimaru, Tobirama laments that he was using his technique again so easily, to which Orochimaru answers that it was not hard and that it shouldn't have been created. When his older brother, agreeing with Orochimaru, starts to reprimand him for his having done so, Tobirama silences hm, saying he was talking to Orochimaru, who then states that he had revived them this time to answer some question for Sasuke. Learning that Sauske was an Uchiha, Tobirama negatively states it was not surprising to see he was with the enemy, which Hashirama angrily reprimands him for. Lamenting that he expected the Uchiha clan would attempt a coup eventually after Hiruzen talks with Sasuke about his brother, Tobirama listens as Orochimaru states he was the one who had cornered them by creating the Konoha Military Police Force, which Hashirama again reprimands him for, as he had told him many times not to persecute the Uchiha clan.
Tobirama tells his brother that he had merely tried to give them a job they would be good at, saying he knew as he did that the Uchiha were "a clan possessed by evil. Intrigued by this, Sasuke asks Tobirama what he means, and he states that the Uchiha were a clan that valued love more than any other and that if they lost someone they loved, an even stronger hatred would emerge, making the Uchiha member with it impossible to handle, citing Madara Uchiha's case as an example, to which his brother states that Madara loved his brother, Izuna, very much, probably more than Sasuke did his brother, Itachi Uchiha. Tobirama goes on to state that he had tried to find a way to channel the Uchiha's power in way that would be helpful to the village, but also that if they ended up destroying themselves for its sake it cannot be helped, which his brother again reprimands him for, saying there was no need to talk that way in front of Sasuke, who then silence's them both. Hearing Sasuke talk about revenge against the village, Tobirama prepares to attack him, but his brother releases a burst of chakra, causing the room to begin to crumble and orders him to back down, which he then does unhesitantly, saying to Hashirama that he didn't have to release him chakra in that manner. Upon hearing that Orochimaru would limit their movements if they tried to leave, Tobirama tells him of his belief that the latter was misunderstanding something and says that as the one who invented the technique, having been brought back with his full power this time due to Orochimaru's improved accuracy, he would not allow him to control him. Saying to his brother that he would go to face Madara, Tobirama was paralyzed by Orochimaru, who had used Hashirama's cells to strengthen his hold.
After Hashirama had told their past story about Madara and the village to Sasuke, Tobirama told him that Itachi was not alone amoung the Uchiha in that way, saying one of his own squadron, Kagami Uchiha, also shared those ideals and denied that he despised the Uchiha, just that they were always a clan that caught his eye because he was wary of any that posed a threat to Konohagakure, but that their loyalty and commitment was second to none. Tobirama goes on to state that Hashirama's notion about what founding the village would bring didn't go well and that he was too naive and Madara too skeptical, before declaring that as Second Hokage he had tried to find a medium between those two extremes so that Konoha could prosper. Somewhat surprised when Sasuke decides to try and save Konohagakure instead of destroy it, Tobirama tells his brother that he can't teleport them as they are still bound by Orochimaru, who agrees to come with them to the battlefield. Heading outside, Tobirama answers his brother's question about Karin, the last member of Sasuke's team, when she arrives, saying that she was from the Uzumaki clan after sensing her chakra. After Hashirama gets worked up and asks the other Hokage to continue using their vigilance to save the village they love, Tobirama laments this and places his hand on his brother's shoulder. As the Hokage each jump down onto their heads carved into the cliff, Tobirama states that he will crush Madara with his own hands this time. After he finishes teleporting himself, Hashirama, and Hiruzen to the battlefield, Tobirama, upon seeing Minato got there first, states that his teleportation technique pales if compared to the latter's. After Minato activates his Nine-Tails chakra cloak and confirms that he had set up their places for their collab technique, Tobirama praises Minato, saying he thought quick on his feet. When his brother rallies them, Tobirama and the other Hokage activate the Four Red Suns Battle Encampment Technique to trap the Ten-Tails.
After it prepares to use anothe rone of its gargantuan Tailed Beast Balls, Tobirama and the other Hokage block the enormous power of the blast, which only manages to blow out the top of the barrier. Watching on as Sasuke and Naruto work together and manage to set the Ten-Tails ablaze with black flames from Amaterasu, Tobirama is impressed and praises them, saying attacks like that would be hard, even for two who had been paired for years. After Obito Uchiha, Madara's apprentice arrives back on the battlefield and Madara had begun to force him to use the Samsara of Heavenly Life Technique to revive him, Tobirama creates two shadow clones, that being his limit while maintaining the barrier, to combat Madara, along with an additional six clones his brother created. However, Minato thwarted Madara's revival by using a shadow clone and his Flying Thunder God Technique to strike Obito down, a feat which Tobirama deciphers. After Obito then used the opportunity to become the Ten-Tails jinchuriki himself and destroys the barrier and restraints, Tobirama is collectively shocked along with the other Hokage, and dispels his clones, before confronting Obito with Hashirama and Hiruzen. When Hashirama declares that Obito is even stronger than he is, Tobirama states that even now, with their clones dispelled, they are outclassed. Before either can react, Tobirama and Hashirama are ripped through like paper by Obito. Reminding Obito that he had created the Impure World Reincarnation and its tactics, Tobirama utilizes his Mutually Multiplicating Explosion Tags technique after his brother's wood clone restrains him, and while the massive explosion destroys himself and the clone, it does Obito no harm at all. Later, after reforming and seeing the massive danger Minato, Sasuke, Naruto, and Gamakichi were in following Obito's new mastery of the Ten-Tails power, Tobirama uses a shadow clone and grabs the mini tailed beast ball about to explode in their presence and teleports back to Obito, having branded him with a seal for his space-time technique, and tells him he has a gift for him as the ball explodes.
Afterwards joining the others himself, Tobirama tells Naruto that it is Minato who was copying his technique and that he would prefer to be shown the respect of the Second Hokage when the latter mistakes that he copied Minato's style. After seeing Obito completely blocked the explosion, Tobirama asserts that it would not be easy to land an attack on him. After Minato suggests him using his Spiral Flash Ring Dance Howl Technique to create an opening, Tobirama states that he sometimes left him at a loss for words and that his technique was almost enough to make a grown man laugh, but that under the circumstances he was in no position to laugh. After Minato states that they would have to use the Instananeous Swapping Flying Thunder God Technique against Obito, Tobirama brands him with the seal for his space-time technique, which Minato does the same to him with his Flying Thunder God Technique, afterwards teleporting to Obito and later using the technique Minato mentioned to switch his place with the latter and cause Obito to get struck by Naruto's Rasenshuriken, which Sasuke covered in Amaterasu. Returning to Minato's side, Tobirama's states that Obito certainly felt that attack, but was shocked to see the black flames part, and Obito emerge unhurt by the attack. Noticing that Minato's arm still hand't regenerated, Tobirama asserts that something was amiss, and after Obito's following statement, becomes shocked as he recognizes Obito's technique. Tobirama states to Minato that Obito was using Onmyouten, a technique capable of nullifying all other ninjutsu, and that their bodies will not regenerate if damaged or destroyed, telling Minato not to count on his arm regenerating quickly. After Gamakichi uses a Water related attack, Tobirama expresses surprise that he was from Mount Myoboku.
Noticing that Obito was not able to nullify the attack, Tobirama becomes surprised and, after Naruto activates his Sage Mode and Rasengan technique, Tobirama teleports him above Obito, who Naruto successfully injures with the Rasengan as it was made from senjutsu chakra, which, as Tobirama contemplates, Obito can not counter with his new powers. Impressed with Naruto, Tobirama contemplates that it felt as though he were fighting alongside Hashirama. After Obito then guarded his back, Tobirama reasons that sooner or later he will be hit by a powerful attack if they keep using this method of attack. After Obito prepares an enormous attck with a giant tree that has four Tailed Beast Balls and cuts of any aide from the rest of the alliance, Tobirama asks Minato if he could handle two of the balls, but the latter replies that without a seal, he could only handle one. After Naruto and Minato manage to save everyone from obito's attack by melding theirs and Kurama chakra into one and giving everyone some of it, Tobirama comments that Minato techniquue had saved everyone for the second time. Explaining that how Minato and Naruto saved everyone worked in the same principle as the Shadow Clone Technique, Tobirama annoyingly told Naruto that he was the one who invented the technique following more oblivious statements from Naruto. After Naruto activates a large amount of Kurama's chakra and leaps to attack, Tobirama, noting his fervor was admirable, states there was no way possible that he could have forgotten only Sage techniques work against Obito already, as that would put him on a whole new level of idiocy. When answers that he did, Tobirama concludes that he actually found a bigger idiot than his brother. After Naruto and Minato prepare a giant Rasengan infused with nature energy, Tobirama teleports them to Obito, who blocks them attack, causing Tobirama to reason that the attack failed because they telegraphed it, stating fighting using the Flying Thunder God technique alone would be tough. After Naruto prepares a Tailed Beast Ball with nature energy for the same reason, Tobirama becomes impressed, contemplating that Naruto may become an even greater Hokage than Hashirama.
After Obito releases the Ten-Tails in its final form, the Shinju, and it begins to attack everyone and steal their chakra, Tobirama uses his Water Release to try and rescue Naruto when he gets caught, but it just regenerates the damage done. Charging towards Naruto, Hiruzen suddenly arrives and rescues him, and Tobirama teleports them all back to where Sasuke was. After seeing Sasuke merge his Susanoo with Jugo's Cursed Seal's senjutsu, Tobirama contemplates that he was an Uchiha as prodigious as Madara himself, later comparing Naruto to his brother. After Naruto and Sasuke team up to engage Obito, Tobirama tells Minato that he will use the link between his and Naruto's chakra to teleport anyone in peril with his Body Flicker Technique out of harm's way, doing so with two shinobi quickly thereafter. After Obito was defeated and Madara fully resurrected, Tobirama, after the latter had captured the tailed beasts, teleported behind him and tried to attack him, only for Madara to dodge him twice and defeat him by stabbing several chakra receiver rods through his pressure points, depriving Tobirama of his immense power and mobility. After Madara laments his method of attack and throws another rod into his head, Tobirama says doing anything to him now is worthless with his current state and asks Madara why he is doing all this. The two discuss the nature of Madara's Eye of the Moon Plan, with Tobirama coming to agree with Madara on his dream world statement, but spitting needles at him to distract him from Sasuke's attack from above, mentally deciding Madara should be allowed to succeed with such a plan. Madara, however, counters them both and, against Tobirama's pleas, stabs Sasuke through the chest with his own sword, much to the Senju's disgust. Noting his inability to even so much as move, Tobirama, after someone shows up by Sasuke, wonders who it is.
The person turns out to be Kabuto Yakushi, who saves Sasuke from his otherwise fatal wound. After Sasuke awakes, he pulls the rods out of Tobirama's back, with him telling him he can teleport only one with the little chakra he has left and sending Sasuke to Naruto's side. When Madara later activates the Infinite Tsukuyomi, a stunned Tobirama, immune to its effects as a non-living entity, laments this in fear and later wonders why its not effecting him as well. He laters senses the massive and overwhelming chakra of Kaguya Otsutsuki, his mightiest ancestor newly revived in Madara's immortal body, and heads for the position he felt it arise. gathering there with all the other undead Hokage, Tobirama asserts that Madara, dead or alive, seems to have accomplished his Infinite Tsukuyomi and proposes using the Impure World Reincarnation on the lower half of Madara discarded earlier to see if he was dead and ask him what had happened, to which his older brother objects. After a chakra incarnation of the Sage of Six Paths emerges from Madara's lower half and explains the situation to them, Tobirama told him to keep further recap brief. After the Sage finished and summoned the souls of many of the previous Kage to help as well, Tobirama and the others work together with them for the Sage and teleport into and back from his mother, Kaguya Otsutsuki's dimension with Team Seven and the dying Madara Uchiha. After a last talk between his older brother and his rival before Madara dies, Tobirama and the other previous Kage were sent back into the afterlife Hagoromo.
Tobirama shares his elder brother's belief in the Will of Fire and was very loyal to Konohagakure. He also has a sense of humor, as was shown in his battle with his former student, Hiruzen Sarutobi. Tobirama has a negative attitude towards the Uchiha for certain aspects about them which, though they love each, has caused his elder brother, Hashirama Senju, to heavily reprimand him more than once. Despite this, however, Tobirama has claimed to Sasuke Uchiha that he does not despise the Uchiha and that they were simply a clan that caught his eye easily do to the fact that he always watched any clans that were a threat in any way to Konohagakure. However, Tobirama deeply depises Madara Uchiha, shown in his desire to crush him personally after his second revival and in his discrimination against Madara, which eventually caused the latter's final battle with Hashirama. Tobirama is more authoriative and stern than his more laid back and jovial elder brother and has been able to subdue him at times, during which Hashirama would simply sulk and obey his commands. He is also not above scolding him at times, as he stated that he was too naive in his thoughts about what building the village would bring. However, whenever Hashirama gets serious, Tobirama is, in turn, subdued by him and seems to fear his brother when he is angry. Despite this, he cares about Hashirama very much, once even attempting to convince their father, Butsuma Senju, not to harm him, saying Hashirama was simply overcome by his emotions and seems to hold him in high regard, once even implying that he thought Hashirama should be the First Hokage instead of Madara Uchiha.
Tobirama is an immensely powerful shinobi, considered one of the strongest of his time, who was strong enough suceeded his elder brother, Hashirama Senju, as Second Hokage. Madara Uchiha even openly admitted that in life, he and Tobirama weren't far apart in power, despite the former still being stronger than him. Tobirama is the most powerful Water Release user in the series, able to create water from air with no water source nearby and use it with immense power in high-scale techniques. After their first revival, Tobirama showed great teamwork ability with his elder brother during their battle with Hiruzen Sarutobi. Tobirama is a very gifted sensory-type shinobi and has the ability to sense enemies in an area by touching the ground and can detail how many there are the same way. He was even able to sense Madara's chakra in the battlefield a long distance away. Tobirama is also very skilled at space-time techniques, as stated by Minato Namikaze, the Fourth Hokage. A skill that his elder brother apparently holds in high regard. Despite openly admitting his own skill with it was less than the latter, Tobirama was the inventor of the Flying Thinder God Technique that Minato's famous for. Tobirama is also a highly skilled and dangerous swordman, so much that he was able to fatally wound and defeat Izuna Uchiha, Madara's younger brother, considered his equal, before he could even react with one attack with his Flying Thunder God Slash technique, despite the latter's possession of the Mangekyo Sharingan. Tobirama also has very strong chakra, able to make a wall crack by simply placing one hand on it and releasing chakra. Tobirama also has a high-level intellect, as he created the Summoning: Impure World Resurrection technique, which he quickly labelled a forbidden technique and didn't finish. However, he gained enough recognition for it that some revived by it, like Mu, believed Tobirama had used it. As its creator, Tobirama was able to resist Orochimaru's control until he used his brother's cells to strengthen his hold.