Ryukotsusei
Ryukotsusei is a dragon demon from the anime series Inuyasha created by Rumiko Takahashi. Alternative spellings include Ryuukotsusei and Ryuukossei.
Ryukotsusei is a taiyokai, a great monster. He is gigantic in size with white/silver hair and glowing red eyes. On his forehead is a mask through which the demon speaks. He is extremely powerful, can fire a massive energy blast (a breath weapon of sorts) and has very tough armour.
Ryukotsusei was the mortal enemy of Inuyasha's father. Inuyasha's father sealed the demon but died as a result of the fight. Inuyasha learns this (in episode 53) whilst trying to discover how to make his sword (a yokai blade called Tetsusaiga or Tessaiga) lighter and easier to use without transforming. He is told that all he has to do is to pierce the dragon demon's heart and thus surpass his father.
This task should be easy since Ryutoksusei is sealed. However Naraku removes the seal and awakens the dragon. This forces Inuyasha to fight head on, which he has previously stated is more his style.
There follows a heated battle which Inuyasha barely wins. At the end, the Tetsusaiga is indeed lighter and Inuyasha is also able to use it to create a Wind Scar (Kaze no Kizu) whenever he wishes.