Ryūkotsusei

"My body is mightier than iron!"

- Ryūkotsusei

was an extremely powerful dragon daiyōkai who terrorized the Plains of Musashi until he was confronted by the Inu no Taishō and sealed to a cliff face in the Valley of Ryūkotsusei. The wounds that Ryūkotsusei inflicted on the Inu no Taishō ultimately led to the latter's death.

Many years later, Ryūkotsusei was reawakened and brought out of dormancy by the hanyō Naraku. Ryūkotsusei had no intention of exacting revenge on Inuyasha, the younger son of the Inu no Taishō, to suit Naraku's purposes, but after destroying Naraku's demon puppet, Ryūkotsusei decided to fight the son of his old enemy to entertain himself. After a very arduous battle, during which Ryūkotsusei was injured many times but never succumbed, Inuyasha defeated the dragon with the Bakuryūha and in defeating Ryūkotsusei, took a major step in the training of his sword, the Tessaiga.

Sealed by the Inu no Taishō
200 years before the shattering of the Shikon no Tama, Ryūkotsusei was a feared daiyōkai and created mayhem across the land. The Inu no Taishō, a powerful dog demon who defended Japan against threats such as Ryūkotsusei, confronted the dragon and engaged him in battle, in order to put an end to his rampage. Ryūkotsusei was a truly terrible foe, however, and not even the Inu no Taishō could defeat him or put him under seal so easily. The Great Dog Demon had faced many powerful demons in the past and had stopped several invasions by powerful daiyōkai and their armies, but Ryūkotsusei was so singularly powerful that the Inu no Taishō was fatally wounded before finally using one of his claws to pierce Ryūkotsusei's thick skin directly above the heart, thus sealing his powers into a state of dormancy.

Revival
50 years later, Ryūkotsusei was visited by the Inu no Taishō's youngest son, Inuyasha, who was on a mission to strengthen his sword, the Tessaiga, by driving it into Ryūkotsusei's heart and killing him. However, Inuyasha's enemy, Naraku, desired to revive Ryūkotsusei, hoping the powerful demon would be able to destroy his hated foe. Naraku used his miasma to disintegrate the claw of the Inu no Taishō that kept Ryūkotsusei under seal. Once done, Ryūkotsusei's powers returned and his heart began to beat once more. As he began to stir, a menacing aura began to collect around him, darkening the skies and summoning storm clouds. As Ryūkotsusei broke free of the cliff he had been sealed to, Naraku called out to him, telling him that Inuyasha was the son of the one who hurled him into dormancy, encouraging him to take avenge himself by destroying Inuyasha.

While the flea Myōga attempted to persuade Inuyasha to flee, Inuyasha expressed his preference for a direct confrontation, since he believed that simply killing Ryūkotsusei while he was dormant to be too cowardly. Ryūkotsusei heard this and asked Inuyasha if he seriously thought that he could defeat him, expressing his amusement at such a notion. Ryūkotsusei lunged forward, crushing the hill Inuyasha had been standing on, proceeding to then fire an energy blast in Inuyasha's direction. While the hanyō dodged the blast, it soon became apparent that Ryūkotsusei's true target was not Inuyasha, but Naraku, who was obliterated. Ryūkotsusei wanted to kill Naraku because he believed him to be an eye-sore. However, after destroying him, Ryūkotsusei recognized that what he had hit was just a demon puppet and not the real Naraku, complaining that such a thing hardly constituted a warm-up.

Ryūkotsusei then turned his attention to Inuyasha, expressing his hope that Inuyasha could provide him with more amusement that the demon puppet had. Inuyasha replied that he was more than happy to oblige and attempted to cut Ryūkotsusei by stabbing into the scar left by his father's claw. However, the attack was futile, and Inuyasha was repulsed. Ryūkotsusei taunted Inuyasha, telling him that it was no use since his body was mightier than any armor. He then stated that it was his turn and fired an energy blast at Inuyasha, who barely managed to dodge it in time.

Myōga yet again attempted to persuade Inuyasha to flee, adding that it was his father's battle with Ryūkotsusei and the wounds he was given that ultimately killed him, shocking Inuyasha. Ryūkotsusei was pleased to hear that his old enemy had perished and asked if Inuyasha had come to avenge his father with a ridiculous sword such as the Tessaiga. Inuyasha said he never even met his father, so avenging him was the last thing on his mind. While Myōga scolded Inuyasha for being a "traitorous" son, Ryūkotsusei took advantage of their arguing to slam his tail against Inuyasha, knocking him into a nearby cliff.

Inuyasha charged at Ryūkotsusei, but was met with a continuous barrage of energy blasts which leveled the surrounding landscape. Ryūkotsusei berated Inuyasha for being so weak, claiming that their battle had become more tedious than he expected and that destroying him relieved him of none of the anger he felt towards Inuyasha's father. Inuyasha leapt to attack again, but Ryūkotsusei slammed Inuyasha into a cliff with his claws, telling him again that he would not be able to defeat him with an inferior sword like the Tessaiga. Ryūkotsusei pressed harder into the rock face, demolishing it and leaving Inuyasha to fall into a deep ravine. After Inuyasha dropped the Tessaiga and plummeted to the bottom of the ravine, Ryūkotsusei fired off yet another energy blast, that left Inuyasha badly injured.

Death
Inuyasha managed to kill Ryūkotsusei by using the Bakuryuha (without realizing it) on one of Ryūkotsusei's Thunder Bullets which tore the demon into pieces. From Ryūkotsusei's death, Inuyasha has surpassed his father. (Also somehow Inuyasha managed to easily defeat Ryūkotsusei using the Bakuryūha even though Inuyasha's father died due to a similiar battle). Sesshōmaru would later follow in these same footsteps, upon forming the Bakusaiga.

Appearance
Ryūkotsusei has the appearance of a typical dragon but with a mask on his head. This mask is Ryūkotsusei's real face as it does the talking and directs the body while the dragon's mouth shoots out powerful energy blasts. Both the mask and the dragon have red eyes. Its long body is covered in thick armored hide which is near impenetrable as Inuyasha quickly realizes. He has two fairly short arms, despite this, he was able to slam Inuyasha up against the cliffside without struggle. Along with his large intimidating body, his demonic aura can easily disintegrate rocks without even having the dragon come in contact with it. Unlike other powerful demons, Ryūkotsusei does not appear to have a humanoid appearance.

Abilities

 * Enhanced Strength: Ryūkotsusei was able to dominate over Inuyasha for the first half of the battle, only to momentarily overwhelmed by his demonic transformation. His full power was not shown in the series, but it was enough for one of the strongest characters in the series, the Inu no Taishō, to be unable to defeat him and had to seal him away, and is the ultimate reason for his death; suggesting he was very formidable.


 * Enhanced Defense: Ryūkotsusei has an incredible armored hide that is nearly impenetrable, even striking the scar Inu no Taishō's claw left in it had no effect. However, when Inuyasha transformed into his full demon form, he was able to inflict wounds on Ryūkotsusei with his claws alone. After Inuyasha repossessed Tessaiga, he was able to stab Ryūkotsusei in the heart and use the Kaze no Kizu on him; however, this attacks only managed to stun Ryukotsusei.


 * Thunder Attack Bullet: These large, powerful, pure white energy spheres are launched out of Ryūkotsusei's mouth and can be fired numerous times consecutively. In the anime, it was so powerful that when Miroku used his Kazaana on one of these blasts, he was only able to change its course slightly. Tessaiga's sheathe was able to protect Inuyasha from one of these attacks.

Trivia

 * Ryūkotsusei appears in the second ending; Fukai Mori. Though, his appearance is somewhat different when compared to his actual debut in the anime.


 * The events of the Inu no Taishō's battle with Ryūkotsusei are further explained in Swords of an Honorable Ruler. The film states that directly after the battle between Ryūkotsusei and the Inu no Taishō, the Inu no Taishō was forced into saving Inuyasha and his mother before he had recovered from the injuries inflicted by Ryūkotsusei, thus contributing to his death.