Takemaru

was a character who appeared in the third InuYasha movie Swords of an Honorable Ruler where he is one of the main antagonists.

History
Takemaru no Setsuna was a jealous human Samurai lord who fell in love with Inuyasha's mother, Izayoi who was, at the time, in love with Tōga and pregnant with their son. His jealousy became so great that he attempted to take her life and impaled her while she was in labor with Inuyasha. When Tōga, came to save her, Takemaru appeared before the daiyōkai warrior and attempted to take him on but his challenge was easily brushed aside, costing him his left arm. Not wanting to let the Inu daiyōkai take Izayoi away, he orders his soldiers to immediately burn down the castle. Takemaru's attempt to keep her for himself was in vain as the daiyōkai utilized Tenseiga to revive Izayoi, allowing her to escape while he fought the desperate Takemaru to the death. Takemaru is killed along with Tōga when the palace collapsed on them.

Later on, the sword Sō'unga (free from Saya) wanders around the land searching for a suitable host after its seal is broken. Reacting to the lingering thoughts of Takemaru, whose skeleton resided in the charred badlands, the evil sword revived him and fed on his desire for revenge against Tōga and his kin. To further sweeten their vengeance, Sō'unga gives Takemaru Sesshōmaru's left arm which was lopped off during the daiyōkai's scuffle with his younger brother earlier in the series. With blade in hand, Takemaru transforms into a Yōkai of death and destruction and takes command of a nearby castle, killing its inhabitants and soldiers whose corpses he uses to raise an army of evil undead as he erects a dark castle to begin his conquest. As Inuyasha's and Sesshōmaru's groups storm the castle, Takemaru comes face to face with Sesshōmaru himself with Tōkijin at the ready.

Though Sesshōmaru is able to easily overpower him in terms of strength and even cuts him down, the Sō'unga simply regenerates him, mocking him that he can't be killed by another weapon already steeped in evil. It is from this realization that Sesshōmaru instead draws forth Tenseiga and attacks again, but Takemaru still lives and continues to mock him, proclaiming that he is disappointing his father's fang. Inuyasha then arrives at the scene and does battle with him after a preemptive Wind Scar attack. Crossing blades, Takemaru looks at Inuyasha and sees his mother in him. Growing colder, he reveals to him that he was the one who had taken his mother's life, greatly angering the half-demon. While Sesshōmaru and Inuyasha begin to bicker over fighting him, Takemaru tries to take this opportunity to kill them both with the Dragon Twister. Inuyasha however rushes forth and drives him back with an unprecedented amount of power. Takemaru is baffled by this and Inuyasha explains that it is his human side that gives him the persistence and willpower to fight to the end as well as the desire to protect those close to him. With one final push, he finally blasts him through a wall, defeating him. His last thoughts and visions are of Izayoi telling to leave the grounds, as it was for his own protection because she wanted him to live, and, finally realizing she didn't betray him and regretting his mistakes, he realizes he never felt hate for Izayoi, as Sesshōmaru uses the Tenseiga to reduce his body to bones and help his soul pass on in peace. His skeleton was crushed following the destruction of his castle.

Personality
Takemaru was depicted as a man who appeared to care for Izayoi but his jealousy over the Dog General consumed him so that he became a danger to all around him and attempted to take Izayoi's life. It seems like Izayoi cared for him as well as she attempted to save him from Tōga's wrath. When resurrected at the behest of Sō'unga, Takemaru's jealousy gradually turned to insanity, wanting to slay each and every human, no matter their age, if they shared a relationship with demons, causing him to view them all the same way that he viewed Izayoi. It is shown though that he wasn't all bad as when he has visions of Izayoi (possibly her soul speaking to him) he realizes he never held anger against her and always loved her.

Physical description
Takemaru first appears as a male human adult with fair skin and black hair tied up in a short fashion. When he was still alive, he wore traditional samurai lord armor featuring a distinct crimson sheen. After being revived as a specter, most of his armor has been worn down but his hair grew to its full length, much past his shoulders. After taking hold of Sō'unga, Takemaru took on a slightly demonic appearance featuring blue spots and markings on the right side of his face and a long horn growing from his forehead along with his hair becoming red and shaggy. His eyes gained a yellow sclera and pupils became red. He wore a dark jacket, white hakama and crimson armor with spikes jutting out and a large blue jewel in the middle of his chestplate.

Powers & Abilities

 * Master Swordsman: As a samurai lord during his life as a human, Takemaru possessed incredible skill in swordsmanship, he could single-handedly kill a guarded fortress of samurai warriors with great ease. When empowered by Sō'unga's demonic energy, he could to go toe-to-toe with Sesshōmaru and even hold both him and Inuyasha back. Also as seen in the flashback 200 years ago, Takemaru was able hold up against Tōga himself (albeit the demon was weakened by his wounds from Ryūkotsusei) with only one arm and being very wounded though the burning mansion they were fighting in collapsed before a decisive winner was determined.
 * Enhanced Endurance: Takemaru possesses enough endurance to recover from a severed arm and sword wounds in moments and proceeded to fight against the wounded and weakened Tōga for some time before they both died in the collapsed burning mansion.
 * Reanimation: Upon being resurrected by Sō'unga as his vessel for the time, Takemaru possesses some unique abilities due to becoming an undead that made him a dangerous opponent.
 * Enhanced Strength: When he was possessed by Sō'unga, Takemaru has enough physical strength to evenly combat against Sesshōmaru and Inuyasha despite the former being a daiyōkai and the latter being a powerful hanyō whom have do doubt greater strength than an ordinary human.
 * Enhanced Speed: As an undead specter possessed by Sō'unga, Takarmu became fast enough to contend with both Sesshōmaru and Inuyasha with him being able to easily parry a blow from the latter with only arm while standing still. Takemaru even managed to slay an entire group of human samurai without getting a scratch on himself.
 * Enhanced Durability: While having Sō'unga in his possession, Takemaru endured a powerful point-blank Kaze no Kizu from Inuyasha that sent him through a wall within the phantom castle and greatly damaged but remained conscious. Though the blow caused him to finally see the sacrifice Izayoi attempted to make for him and the other men at the mansion that caused him to finally pass on.
 * Regeneration: As a result of being possessed by Sō'unga, Takemaru is able to regenerate from even the most fatal of wounds and could even recover from a slash of the Tenseiga as his hate prevented him from passing on.

Weapons

 * Warlord Armor: When he was still alive, Takemaru adorned a set of red armor, including cuirass, gauntlets, grieves and helmet. After his death, this was worn down but restored and transformed after taking a hold of Sō'unga.
 * Naginata: While still a living samurai, Takemaru brandished a samurai spear to kill Izayoi just after she gave birth to Inuyasha though Tōga resurrected her with Tenseiga.
 * Katana: Before dying with Tōga in the burning mansion, Takemaru wielded an ordinary samurai sword in an attempt to defeat the demon.
 * Sesshōmaru's Left Arm: Due to being a reanimated human, Takemaru needed to connect Sesshōmaru's severed left forearm in place of his own severed left forearm in order to use the powers of Sō'unga in particular with that of the Dragon Twister. Though he is unable to fully control the demonic powers of the arm as he commented that the arm doesn't like following his instructions after he used Dragon Twister to slaughter an army of samurai and collapsed in exhaustion.
 * Sō'unga: The third sword once possessed by the Dog General. It fed on Takemaru's lingering desires as a specter and restored him to life and gave him great power, promising him supreme conquest if he was to kill Inuyasha and Sesshōmaru. While their swords, Tessaiga and Tenseiga, could destroy a hundred demons in one swing and save a hundred lives in one swoop, Sō'unga could summon forth a hundred corpses from Hell itself to serve the wielder. Unlike the other two swords, Sō'unga is possessed by an ancient and malevolent demon spirit.
 * Gokuryūha: As a result of wielding Sō'unga, Takemaru can, at will, invoke the powerful Dragon Twister which allows him to summon forth the powers of a hell dragon and utilize its power in the form of a massive twister of demonic power strong enough to level a fully fortified castle single-handed.
 * Phantom Castle: In his attempt at revenge against Sesshōmaru and Inuyasha for Tōga, Takemaru used Sō'unga to create a phantom castle similar to Naraku where he resides in the center while the undead army risen by him fight both groups outside.
 * Reanimation: After killing the samurai army that originally resides in the castle, Takemaru has Sō'unga reanimate them as undead soldiers like him though they act more like mindless zombies incapable of thought and speech. He does this by rising the Sō'unga above while standing in a tower of the phantom castle and then the blade of the sword drips out blood that initiates the process of reanimation when it touches the corpses.

Trivia

 * Takemaru's full title, "Setsuna no Takemaru" (刹那の猛丸, せつなのたけまる), literally translates as "Violent/Savage/Cruel/Bold Circle/Perfection" (Takemaru) "of the Moment" (Setsuna no); and all together (Setsuna no Takemaru) can rather fittingly be transliterated as "In the Heat of the Moment."
 * It is never revealed what the precise nature of his relationship with Izayoi was but it seems that she trusted him to actually be releaved (mistakeningly) when he came to her as she was having Inuyasha and she really did try to save him from the Inu no Taisho (who was her own husband) so it's very possible they were close, maybe friends even.