Tōga

Great Dog Demon (犬の大将, Inu no Taishō or Inutaisho) was a powerful yōkai lord who was known throughout Japan. Never formally addressed with a name, but by fans is some times called Inu-Papa. He fathered two sons by two different mothers: Sesshomaru from an unnamed dog demoness, and InuYasha from a human woman (unnamed in the manga, but named "Izayoi" in the third movie). The Great Dog Demon is first mentioned in chapter twelve of the manga as InuYasha's father, "a demon dog that prowled the lands of the west". The Great Dog Demon's major foe in the manga was the dragon Ryūkotsusei, whom he could not kill but sealed onto a cliff face with his claw; Myōga calls this battle the "cause" of his death.

Overview
In the third InuYasha film, Inuyasha: The Movie 3 Swords of an Honorable Ruler, the Great Dog Demon survives long enough to save Izayoi and their newborn child Inuyasha; still weak from his battle with Ryukotsusei, he dies defending them from a human foe named Takemaru. The gateway to his tomb is hidden in a black pearl (a mystical gem that creates a path between the mortal and spirit worlds) inside Inuyasha's right eye. (I have no clue how they get that in there.) Within the pearl, their father's body is shown as an enormous dog skeleton in a suit of armor: his true form, according to Myoga. The sword Tetsusaiga, forged from the Great Dog Demon's own fang, rests inside this cavernous skeleton, protected by a barrier that repels any non-human with malice toward humans. Because of this, Inuyasha inherits the sword rather than Sesshomaru, this also suggests Inuyasha's father was never bigoted toward humans nor was he evil. Sesshomaru even says that he had a "merciful heart for humankind" it seems that he does have a sense of honor and perhaps wanted both his kind and the human race to live in peace.

Abilities
Much of the Great Dog Demon's abilities are unknown, but it is known that he could change his appearance into a human looking form similar to Sesshomaru and his former mate. His true form was that of a gigantic dog which was far larger then both Sesshomaru's and Sesshomaru's mother's true yokai form. This allows him to move at top speed. He has been stated to be one of the most powerful yokai in the series by Myoga and Totosai. Despite his great power, he was unable to kill Ryukotsusei and was only able to defeat him by sealing his powers away. The aftermath of the battle lead to the dog demon's death. By the end of the series both his sons, Sesshomaru and InuYasha, surpass him, though not in raw strength, but in their abilities to fend for themselves without the need of his protection.

Other than that, he seems to be arguably quite powerful, as he is shown wielding the Tessaiga very nimbly and proficiently, and using two powerful Wind Scars to annihilate dozens of foot soldiers and tear down a fortress wall.

Relationships

 * Sesshomaru's Mother: She was his first wife and had Sesshomaru as a child, but he left her for Izayoi. She was seen in the manga and she then appeared in the anime's second series, InuYasha: The Final Act. Also being a Daiyokai like her husband, she can also transform into a giant dog.
 * Izayoi: It is unknown when they first met, but they ended up falling in love and having a half-demon child, InuYasha. After his last battle, he rushes to save her without first tending to his wounds. He fights through the soldiers only to find her already dead. Using the Tenseiga, he brings her back to life, giving her the Cloth of the Fire Rat, and tells her to escape with their newborn son whom he names InuYasha. His last words were: "Izayoi...You must live. Live a long life. Live long and well with Inuyasha." This showed that the Great Dog Demon did deeply care about his sons, not seeing them as tools of heritage.
 * Inuyasha'- being born only moments before his father's death, Inuyasha never met his father. In Swords of an Honorable Ruler, after saving Izayoi from Takemaru with Tenseiga, he named his son Inuyasha. According to Myōga, Inuyasha is able to use his sword Tessaiga because he protects Kagome, who is human, mirroring his relationship with Izayoi.
 * Sesshomaru - his relationship with his first son is somewhat strained because he left his mother for Izayoi. In Swords of an Honorable Ruler, one moonlit night, his gravely injured father asked him if he had "something To Protect". Sesshomaru knew that it was his father's final test for him, but he was too proud, and Sesshomaru stated that his answer was "No". And so the Tenseiga was passed to him after his father died saving Inuyasha and Izayoi. At first Sesshomaru felt nothing for the Tenseiga as it had no destructive power whatsoever, but as time passed, he started to understand and respect its power. He also came to understand his father's cryptic words from long ago. And now, with something to protect, Sesshomaru has become the most powerful yōkai in the world. His vast powers are tempered with tolerance and restraint, as his father had intended all along.

Enemies
A recurring plot device throughout the series is old enemies of Inu no Taisho returning and seeking revenge through defeating his sons.


 * Ryukotsusei: a dragon demon with powers that resemble lightning. Inu no Taisho only managed to seal him to a cliff with his claw, as it was said Ryukotsusei was too powerful; furthermore, it is implied that the wounds Inu no Taisho received in that battle lead to his demise during his battle with Takemaru of Setsuna in the third movie. Many years later, Naraku releases Ryukotsusei's seal hoping the dragon would kill Inuyasha, who coincidentally was there to defeat Ryukotsusei whom was still weak from the 200 year seal.


 * Hyoga: a moth demon from "the Continent", or as some have inferred, China. This is yet another demon that Inu no Taisho managed to seal but not defeat. Sealed within the Tree of Ages, Hyoga is absorbed by his son and successor Menomaru, who in turn tries to kill Inuyasha and absorb all living souls on earth.


 * Shishinki: the original wielder of the Meido Zangetsuha. The battle between him and Inu no Taisho is implied to be inconclusive though it is revealed Shishinki was terribly injured. He seeks to kill Inuyasha and Sesshomaru as revenge for stealing his technique.
 * [Panther King]: a demon that Inu no Taisho manage to defeat long ago. Yet his tribe used the stolen sacred jewel shards to resurrect him. But was killed by Inuyasha and Sesshomaru.

Aliases

 * Father (by Sesshomaru and a few times by Inuyasha)
 * Dearest (by Izayoi)
 * Demon (by Takemaru)
 * Master (by Totosai, Myoga, and Saya)
 * My Old Man (by Inuyasha)
 * Great Dog General
 * Inuyasha's father/Sesshomaru's father