Tōga

Great Dog Demon (犬の大将, Inu no Taishō) was a powerful yōkai lord who was known throughout Japan. Never formally addressed with a name, 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. 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 left her for Izayoi. She was seen in the manga and she then appeared in the anime's second series, InuYasha: The Final Act. Such as also being a Daiyokai like her husband, she can also transform in to a giant dog which was also passed on to her son.


 * 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.

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 Takimaru 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


 * Hyoga: a moth demon from "the Continent", or as some have infered, 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.