Kōga

is the young leader of the eastern yōkai-wolf tribe, or the Yōrō clan, which is nearly wiped out by Kagura and Naraku. He first meets Inuyasha as an opponent in battle, but later becomes a reluctant, occasional ally despite maintaining a strong sense of rivalry with the 'useless mutt' about their relative combat strengths, as well as Kōga's persistent courtship of Kagome.

Although Kōga often flirts with Kagome, it is later revealed that he has promised Ayame, another wolf demon, to make her his wife. Later, Kōga tries to get Ayame to give up her pursuit by saying he will only marry someone who can sense sacred jewel shards. These events don't happen in the manga because Ayame is an original character made especially for the anime. Kōga married Ayame and became the new chief of the wolf demon tribe.

Kōga is introduced in the series with three Shikon shards in his possession; two embedded in his legs and one in his right arm. He loses the shard in his arm during a fight with a bigger version of the Bird of Paradise, and the shards in his legs are eventually taken away from him by Naraku, gravely weakening him. After Kikyō's death at Naraku's hands, Kōga decides to parts ways with Inuyasha, Kagome, and the rest of the group, leaving the battle with Naraku up to them. He also tells Kagome that she may leave Inuyasha and come to him at any time.

History
Prior to his meeting Kagome and her friends, not much is known about his past or his parents. It seems that he is the youngest leader of the wolf-demon tribe thus far and he once promised a much-younger Ayame to take her as his wife. This occurred during a lunar rainbow, though he later denies that this incident ever occurred. It also seems that he has a solid, possibly long friendship with Ginta and Hakkaku.

During the Story
Kōga is first seen pursuing and killing a wolf demon who betrayed him by stealing a sacred jewel shard from him. The other wolf demon took refuge in a hut that belonged to Rin (who later becomes Sesshōmaru's companion). After mercilessly killing the other wolf demon and taking back the stolen shard, Kōga left his wolves to eat the villagers, but they called him back when Inuyasha started to slaughter them. Upon finding out that Inuyasha killed his underlings, Kōga and Inuyasha immediately develop a rivalry with one-another, despite the fact that Inuyasha is a fellow canine. After discovering that Kagome could sense Shikon jewel shards, Kōga kidnapped her in order to have her find the Bird of Paradise which possessed a sacred jewel shard, and through her cooperation, Kōga eventually falls in love with her, though his feelings were one-sided. After Kōga became wounded, Kagome allowed him to flee despite Inuyasha's protests. Afterwards Inuyasha gets mad at Kagome, and eventually Kagome realizes she was ungrateful to Inuyasha, who had come to save her, and the two of them make up.

Later, Kagura, an incarnation of Naraku, tricks members of the demon-wolf tribe into coming to Naraku's castle under the premise of gathering sacred jewel shards; she slaughters them all. Soon afterward, Inuyasha and group appear on the scene, and Kagura uses her dance of the dead to cover Inuyasha in the slain wolf-demons' blood. Kōga then shows up and sees all of his comrades corpses along with Inuyasha covered in their blood. Believing that Inuyasha murdered all of his friends, he tries to kill the half-demon in a rage. Kōga eventually learns that his comrades were slain by Kagura, a minion of Naraku. He was also poison by a fake jewel shard which Kagome destroyed after Kagura left the castle. After this, he vows to kill Naraku and avenge the deaths of his comrades.

After his first encounter with Inuyasha, Kōga regularly appears in the first half of series looking for Naraku, much like Inuyasha's group. He often gets Inuyasha upset to the point where Kagome has him "sit" to avoid conflict.

During the Mount Hakurei arc, Kōga spends most of his efforts trying to find a way inside the barrier surrounding the mountain, all the while fighting members of the Band of Seven. When Naraku makes his move inside the mountain, he engulfs Kōga in his walls of flesh with the intent of swallowing the wolf-demon along with the jewel shards in his legs; however, Kōga is later freed by Kagome's arrow and saved by Inuyasha.

He wasn't seen again for much of the story after Mt. Hakurei, not until Mōryōmaru's creation, at which point he decided to obtain the Goraishi to gain the power needed to fight his foes, who are also growing in strength. He eventually loses his shards and decides to retire from fighting Naraku, leaving the fight to Inuyasha's group.

Later life
Kōga married Ayame after the Shikon no Tama's destruction, and their tribes joined. However this event only happened in the anime and did not occur in the manga.

Personality
Kōga is almost always completely straightforward and his simple and clear demeanor bears no shadow of Magatsuhi. Initially, he had no human feelings, such as sympathy or having concern for the weak, shown in his first appearance when he let his wolves kill the villagers of the village where a betraying wolf demon ran to. He changes his ways due to Kagome for her acts of kindness. Gradually, he develops a sense of compassion towards humans due to his exposure to Inuyasha's party, mostly through Kagome's influence. His attitude is mostly wild and he is only concerned with survival. Much like an actual wolf is, he is keenly in tune with his instincts and will not hesitate to follow them (such as running away when the situation is not in his favor).

Kōga is the young leader of the Wolf-Demon clan. He has complete trust in his comrades, and will always protect his pack regardless of the danger he faces on the front-lines. He will punish anyone that hurts his pack, regardless of who they are. However powerful an enemy may be, he will swear revenge. With his pride as a Wolf-Demon clan member, his conviction is unwavering. Kōga hurried to the castle to save his comrades after learning they'd been slain.

The relationship between Kōga and Inuyasha is sometimes that of collaborator. Since they met, they have been rivals for the love of Kagome. They each realize the power of the other but refuse to admit it. It is just like a cat and dog relationship, but they grow to trust each other little by little. They pursue the same enemy, Naraku, and sometimes exchange information. In a serious crisis, they cooperate with each other.

Kōga rarely makes battle plans. His actions are basically animalistic hit-or-miss. But he sometimes exhibits surprising strategies with his naturally sharp instincts.

As long as he likes something, he is not concerned with the feelings of others. He simply proceeds in one direction. Kōga aggressively told Kagome that she would be happy if she were with him. He approached Kagome forcibly even though they had just met. His expression of love is pure and he goes to meet Kagome wherever she may be. If a woman that he likes relies on him, he becomes elated, forgetting all about combat.

Physical description
Kōga has blue eyes and black hair that is always tied up into a ponytail with a brown cord. He wears a brown wolf pelt. He has a tail that is like a bushy wolf's tail, which is the same shade of brown, though it is in fact part of his body. Kōga has a brown wolf fur head band, black hair, and wears silver and black armor. Kōga also has brown wolf fur as shoulder plates. He carries around a sword, entirely for decoration, however he does use it once as a last resort. His ears are pointed and resemble those of Sesshōmaru and other demons. He is also usually seen with his posse of wolves and wolf demons, namely Ginta and Hakkaku.

Powers & Abilities

 * Whirlwind: Kōga's method of transportation. Whenever on the go, he is enveloped in a high-speed tornado. Despite its effectiveness, Kōga never actually uses it in battle. He usually outruns Ginta and Hakkaku due to his impatience and the fact that he is so much faster than they are.
 * Strength: In his battle with the Wolf Guardian, Kōga could easily lift the body of the Goraishi Guardian and throw it. Also he has proven to scuffle with Inuyasha, who is very strong, in mere fist fights. In The Final Act, he was also able to hold Inuyasha's Tessaiga with little effort despite being greatly hurt.
 * Jewel Enhanced Abilities: Kōga originally possessed three jewel shards: one in each leg and one in his right arm. These allowed him to run at exceptional speeds and increased the strength of his right arm. He eventually lost all three shards throughout the series, losing the 1st one from his arm at the end of episode 37.
 * Stamina: Being a full-fledged demon, Kōga has incredible stamina. He states that he can run three days non-stop and he can fight for a long time even when he is wounded.
 * Endurance: Being a demon Kōga has enhanced endurance. Even when he is seriously wounded he can still fight. In the battle with Ginkotsu and Renkotsu he defeated them even though his legs were badly injured. Further proof of his endurance is then Naraku impales Kōga in the legs and drags him into his own body. While trapped within Naraku, his miasma that could melt forests and mountains failed to melt or even severely injure Kōga.

Weapons

 * Goraishi: A claw that Kōga earns from his ancestor spirits so that he can avenge the deaths of his comrades and destroy Naraku. It creates energy blasts that are equal to that of a fully-powered Wind Scar. The claw shields him, barely, from Naraku's corruption of the jewel but it was only able to protect him once. The Goraishi have literally become a part of Kōga.
 * Sword: Kōga has a long sword he carries at his hip, but he has never used it during the series. This is because his Wolf-Demon instincts do not rely on weapons. However, he did use the sword once in Chapter 340 of the manga. In a later chapter he states that he stole it from a human by choice, though it was mentioned that is was merely a decoration, not for self-defense.

Relationships
Ginta and Hakkaku are Kōga's two main traveling companions, and his best friends. He cares very deeply about them, as seen when he attempted to get the Goraishi, saying that he would rather not have the weapon's power if it meant sacrificing the lives of his comrades. Ginta and Hakkaku are often seen out of breath, chasing after Kōga because they are unable to keep up with his awesome speed. They are extremely loyal to Kōga, and are always looking out for his best interest; they generally obey his every command as well. Though on one occasion, Ginta and Hakkaku disobeyed him, but because they feared a confrontation would take place between him and Inuyasha's powerful brother, Sesshōmaru.
 * Ginta and Hakkaku

Kōga first met Ayame as a young girl after he saved her from a demon. Ayame is the granddaughter of the chief in the northern mountains. Kōga promised to marry her when she was younger, so Ayame comes searching for Kōga in order to return to the northern mountains and restore balance among the tribes. After Kōga refuses to go with Ayame, she returns to the mountains alone, and sometime later the two meet each other. In the end of the anime series, Kōga marries Ayame not knowing that Kagome had returned and married Inuyasha.
 * Ayame

Inuyasha was seen by Kōga as a love rival for Kagome. They have many insulting names they call each other- Inuyasha is usually Mutt-Face and Kōga is usually Wolf-Cub. Although later they do become allies and even view each other as friends (though they will never openly acknowledge it). During most of their meetings, Kōga causes Inuyasha to almost draw Tessaiga, forcing Kagome to give a sit command, much to Inuyasha's annoyance. Kōga learns of Inuyasha's weakness during the new moon during his second encounter with Kagura, but chose not to take advantage of Inuyasha's mortal state. The two of them would often bicker about who would get to Naraku first and kill him, because they both sought a form of vengeance. After Kikyō's second death, Kōga (in his own way) tries to console Inuyasha from his grief, and after his final departure, Kōga trusts him to finish off Naraku for good.
 * Inuyasha

At first, Kōga kidnaps Kagome and Shippō only because Kagome can see the sacred jewel shards in the Birds of Paradise. Later in the next episode, Kōga claims Kagome as his "woman," receiving a slap from Kagome. When Kōga starts to insult Inuyasha even purposely mispronouncing his name, Kagome sticks up for him and says: " His name isn't InuTrasha, so don't insult him! He's brave, courageous, really good-hearted when he's not being a jerk, and he's got a great name so say it right. Inuyasha." Kōga threatens to kill him once he sees Inuyasha again. During the series, Kōga saves Kagome multiple times while Inuyasha is preoccupied attacking other demons or the enemy. Inuyasha tends to get jealous when Kagome is kind to Kōga before chasing him off. Kagome however doesn't have any feelings for him and only thinks of Kōga as a friend.
 * Kagome Higurashi

Throughout the series, Kōga is fully aware of Inuyasha's love for Kagome, but is completely oblivious of Kagome's love for Inuyasha, however during Vanished in a River of Flames that is when Kōga finally realizes that Kagome is in love with Inuyasha after he saw how happy and relieved she was when Inuyasha was revealed to be alive. However, despite discovering Kagome's true feelings for Inuyasha, Kōga vowed he would never give up on having Kagome for himself. In "The Final Act", when deprived of his Shikon shards, Kōga retires from battling Naraku, telling Kagome to come to him if she ever gets tired of Inuyasha.

Kōga met Inuyasha's half-brother in Episode 99. In the episode Kōga meets Sesshōmaru and they seem to be off to a horrible start when Kōga talks about Inuyasha (being a half demon). Sesshōmaru's companion, Rin, was originally killed by Kōga's wolves until Sesshōmaru brought her back to life with his Tenseiga, and she even remarks that she remembers him. However, during their encounter, Rin is attacked by a centipede-like demon, and Kōga kills it before Rin is killed. Sesshōmaru and Kōga seemed to have a mutual understanding, but it still seemed as though their confrontation would have turned into a battle if Kōga had not have saved Rin. Sesshōmaru later remarks that he would have killed Kōga if the wolf hadn't shown that he has altered his ways. Similarly, Kōga tells Ginta & Hakkaku that while he has a problem with Inuyasha, he's yet to have any reason to hate Inuyasha's older brother.
 * Sesshōmaru

The two have only met in InuYasha: The Final Act. When she detects and warns Kōga not to charge for Naraku or his incarnations recklessly (because of his possession of the two out of three remaining jewel shards). At first, he rejects her assistance, until he learns of her promise to use the shards to kill Nakaku while saving Kōga's life, which piqued the wolf-demon's curiosity. During his travels with Inuyasha's group and her second death against Naraku, he gained respect towards her for honoring (part of) the promise she made to save his life, and was present during her final moments. Needless to say, he also gain knowledge (presumably from Inuyasha's group) of the fact that she and Inuyasha used to be lovers (much to the hanyo's annoyance).
 * Kikyō

Trivia

 * Despite being a main character, Kōga does not appear in any of the four InuYasha movies.
 * Kōga constantly tries to woo Kagome, but to no avail.
 * Kōga's love for Kagome is one-sided.
 * It was Kōga's wolves that originally killed Rin.
 * The scent of dog gives Kōga heartburn.
 * In the Holy Pearl both You Ming and Rou Di are based off Kōga and Miroku
 * Kōga is similar in appearance to Ryōga Hibiki from Ranma ½, who is also romantically interested in the female protagonist and has a similar name that in part means "fang".
 * Because he is a full-blooded demon it's quite possible that he is much older than he looks and likely has semi-immortality.
 * It's quite possible that Kōga might be able to shift into a wolf form but it is never shown in the manga or the series.
 * All of the wolf demon tribe members wear wolf fur because it is a way to respect and remember comrades who have died.
 * None of the wolf demon tribe members have tails except for Kōga.
 * Despite wanting revenge against Naraku, Kōga was not present for the final battle.
 * Kōga is one of the two main characters to never see Inuyasha in his demon form (the other one being Kikyō).
 * He never draws his sword in the battles.