Seishin Uchiha was born as the younger brother of Fugaku Uchiha. Growing up in the shadow of the would be clan head, he aimed to surpass his brother and gain their fathers approval, very similar to how Sasuke would come to strive in the future. Despite the rivalry between the two brothers, they shared a close bond and could always count on each other in times of need.
Seishin entered the academy at age 6 and graduated at age 8, one year older than Fugaku had been. He awoke his Sharingan at age 10 and had completed it at age 12, all the while being one year older than his brother when he had done the same. When Seishin was 15, both he and his brother were enlisted in the ANBU, Fugaku being 23 at the time. As Fugaku was more experienced in actual combat, he quickly rose through the ranks while his younger brother was stuck in the bottom. After 3 years of constant struggling, Seishin decided that rather than keep running after his brother, he would focus on what he himself was good at. After two years of studying, Seishin was enlisted as a scientist in Konohas laboratory. This was around the same time Fugaku met Mikoto and began to settle down, leaving the ANBU and instead joining the Konoha Military Police Force.
Seishin were present at both Itachis and Sasukes respective births and came to grow close to Itachi in particular. For a time, Seishin acted as Itachis mentor and he was also the one to help Itachi learn how to control his Sharingan, once he awoke it. He was also the one that taught Itachi the kunai exersise that Itachi would later pass on to Sasuke.
Finally feeling free from his brothers shadow, Seishin quickly gained respect for his scientistic skills and chemical knowledge. He worked as a scientist for 5 years and became known as the spirit of chemistry (Kagaku no Seishin). In time, his physique and shinobi skills began to develop along with his high knowledge, as he could put his knowledge to good use during battle. When he reached the age of 25, Fugaku finally acknowledged Seishin as the stronger of the two brothers. This spurred Seishin to find new goals in order to get even stronger, which in turn led to him resigning as a scientist to travel the world.
Seishin spent 7 years on the road and honed his skills, becoming a very powerful shinobi. Sometime during this period, he encountered and fought Tobi. The battle went into a stalemate, where Tobi eventually escaped stating that he still needed to preserve his strength for that. He also encountered Orochimaru at some point and had a brief partnership with him during the development of the Cursed Seals .
Returning to Konoha, he found the Uchiha district in ruins after the Uchiha clan massacre. Finding his brothers corpse in the ruins of his family house,Seishin was overthrown by pain and rage, enough to aweaken his Mangekyo Sharingan . Assuming that everyone else was dead as well, he left to track down Itachi, who he was told had conducted the crime. Upon reuniting with his nephew, the two engaged in battle. At a point, Seishin was given the opportunity to strike down his opponent but in the end couldn't find it in himself to deal the final blow to his beloved nephew and was instead defeated when Itachis Susanoo awoke for the first time.
In the aftermath of the battle, Seishin was approached by Tobi, who offered for him to join Akatsuki. While he declined the initial invitation, he would come to establish a partnership with Tobi, that came to influence the upcoming events. Gaining acces to Hashirama Senju 's DNA through their partnership, Seishin helped Tobi create White Zetsu, as well as implant the DNA in Tobi's own body to prolong his life. He was also the one that implanted Nagato's Rinnegan into Tobi's left eye socket.
Following Akatsuki's defeat and Tobi's death during the Fourth Shinobi World War, Seishin didn't seem to care the least for the death of his partner. He stated to a White Zetsu Clone that "Tobi took too much for granted". Finally gaining full access to Tobi's laboratory, he stole the eyes of his direct anscestor Madara Uchiha and left to build up a new organisation. It is currently unknown what his motives are, but he have stated that "Tobi was an idealist, I am a realist".
When he was younger, Seishin used to be a warm and inviting individual, loving towards his brother and caring towards his friends. He would often show of a happy go-lucky face and was always eager to help others in any way he could. He was described as a hyperactive nucklehead by his older brother, who used to be a more calm individual. During his time in the ANBU, he learned to control his emotions better, to the point of being almost completely emotionless during missions. Despite this, his go-lucky personality stuck with him up until the Uchiha clan massacre.
The loss of his brother filled him with hatred, sorrow and rage. His earlier personality traits were no longer visible the least. Seishin became an avenger that sought to avenge his clan. At first, this anger were directed towards Itachi, who had commited the crime in person, but it was later re-directed towards Konoha's higher-ups after he learned the truth from Tobi.
In the present, Seishin is a cold person that doesn't show personal emotions. He is constantly seen with an intense and sinister look in his eyes, showing that he no longer care's for other people like he used to do. It have been shown that he holds a deep loathing for Konoha and despises the village for the way they treated the Uchiha, also showing great affection for his clan. This affection can also trigger a surge of rage whenever someone badmouths the Uchiha in his prescence, often leaving the victim broken, either through torture using genjutsu or through physical abuse.
In his youth, Seishin used to wear the standarn Uchiha clothing, consisting of a black shirt with the Uchiha crest on his back, beige shorts along with a pair of dark-blue ninja sandals. Along with this, he wore the village's forehead protector during his missions. When he was in the ANBU he used to wear the standard ANBU uniform, consisting of several grey armor plates upon a black outfit, along with a mask that resembled a bird.
Leaving the ANBU, he returned to his normal attire, though he added the villages flat jacket. After becoming a scientist, he added a white coat over his black shirt that reached down to his knees.
When he left to travel the world, he made up a more customized outfit that resembled the Uchiha robes Madara used to wear. He also allowed his hair to grow longer during this time, as he didn't bother to cut it as often as he used to.
In the present, Seishin have began to wear an Akatsuki robe as he aims to revive the organisation for his own purpose. Underneath the robe, he wears a black loose-fitting bodysuit with the Uchiha crest on his back and armor plates on his shoulders. Along with this, he wears a necklace similar to that of the Sage of the Six Paths. He have the standard Akatsuki sandals and black gloves with his Akatsuki ring on his right thumb. His hair is now cut shorter a bit and he have discarded the forehead protector.
Despite growing up in the shadow of his older brother, Seishin would later come to be considered the most powerful of the two. He graduated from the academy at age 8 and awoke his Sharingan at age 10. His have experience from his time as an ANBU and his high knowledge of science and chemistry can be used effectively in battle. Fugaku early noted that Seishin's chakra reserves far surpassed those of his own, showing that Fugaku's fast development would be useless if a battle between the two went into stalemate. He was also able to battle Tobi into a stalemate, despite his opponents ability to make himself intangible. He was also able to fight Itachi Uchiha on equal footing, despite loosing in the end. Despite these accomplishments, it's been awhile since he was last seen in battle and it's hard to determine where he currently stands in terms of strength.
One of the main elements of Seishin's fighting style is his vast prowess in genjutsu. He often uses them if he deems the opponent too weak to waste chakra on. He can cast a genjutsu so strong that he can completely control another being without them being aware of it. Though it rivals the Kotoamatsukami in terms of raw binding power, eye contact is required in order to cast it. He can also turn an opponents genjutsu against themselves, using Demonic Illusion: Mirror Heaven and Earth Change.
After his Mangekyo Sharingan awoke, the first ability he learned to use was the ultimate genjutsu Tsukuyomi. During his fight with Itachi, his skills with it at that time surpassed Itachi's though his limited use of it in later stages of his life left him inferior to Itachi's experienced version.
Aided by the Sharingan, Seishin have gained a superior mastery of Ninjutsu, being able to perform some of them without any visible hand seals. He early mastered all of his clans techniques, beside his brother.
At the mere age of 9, Seishin learned how to perform the Fire Release: Great Fireball Technique, the signature move of his clan and a coming of age rit. He wields Fire as his main element and utilizes it in almost every one of his battles. He later learned to perform the stronger variation of this technique, known as the Fire Release: Great Fire Annihilation and its sibling technique, the Fire Release: Great Fire Destruction.
The second Mangekyo Sharingan ability, that awoke in his left eye, was Amaterasu , the ultimate fire technique. This ability awoke shortly after his battle with Itachi, though he did not practice the use of it due to the side effects of the Mangekyo Sharingan. His skills with it is currently unknown.
When the tailed beasts were released at the end of the Fourth Shinobi World War, Seishin captured the Seven-tailed Horned Beetle and have since been able to summon it at will. How he controls it is currently unknown but it is suggested that it's the doing of his Sharingan.
Uchiha Clan TechniquesEdit
Due to his Uchiha lineage, Seishins first weapon of choice is the Sharingan, which he mastered at a young age. Aside from that, he also mastered the clans coming of age technique at the mere age of 9. He can also use the Uchiha Flame Battle Encampment to protect himself or anything else from attacks.
Seishin awoke his Sharingan at the mere age of 10 and completed it at the age of 12. His skills with it are so vast that he can keep it activated at all times with minimal drain on his chakra level. Utilizing it in battle as his main weapon of choice, Seishin can read an opponents moves and combined with his high knowledge of most techniques pick the most effective way to counter it.
Seishin awoke his Mangekyo Sharingan after the death of his brother Fugaku Uchiha during the Uchiha clan massacre. Using it during his battle with his nephew Itachi, he awoke the Tsukuyomi, the ultimate genjutsu, in his right eye. He would later go on to activate Amaterasu in his left eye. Because of the drawbacks of the Mangekyo Sharingan, Seishin didn't practice use of any of these techniques after his battle with Itachi.
When he couldn't beat his brother in terms of physical prowess, Seishin instead resolved to beat him through his superior mental capabilities. Having worked in Konoha's laboratories for 5 years, as well as being co-operateing with Tobi, withnesses about his unusual high mental capacity. This, along with his long experience, can easily lead one to assume that Seishin is one of the most knowledgable shinobi currently alive.
- Seishin means "spirit".
(To Fugaku): "Why? Why do I keep losing to you?"
(To Itachi) : "I have nothing to say to a filthy traitor like you. Vanish! Tsukuyomi!"