Hōsenki I

is an oyster-demon who cultivates a variety of magical jewels.

He created the Black Pearl in InuYasha's right eye that enabled Sesshomaru to travel to his father's grave and try to steal Tetsusaiga, the sword his father willed to InuYasha. Later in the series, InuYasha's group needs to travel to the nether world and seek out Hosenki, but learn he has died and his son, who shares his name, can not make the gems yet. They find another path to the world where they find the departed Hosenki sitting among the bone's of InuYasha's father's body. However, he had been corrupted by a shard of the Jewel of Four Souls and attacked InuYasha. After Naraku reclaimed his shard, Hosenki returned to normal and taught InuYasha how to use Tessaiga's Kongosoha attack.

Abilities
Kongōsōha: Hosenki is the original wielder of this powerful technique.He is able to send a shower of adamant shards (diamonds) to injure his enemies. It is powerful enough to penetrate Naraku's barrier and it is the only technique that is able to do so. It is also powerful enough to destroy large parts of the cliffs that surrounds the border between life and the afterlife.

Adamant Armor: Hosenki is covered in adamant and because of that he has an incredible defense due to adamant being considered the strongest substance in the world. His defenses are able to withstand Inuyasha's Kaze no Kizu and repeated blows from Inuyasha's Tessaiga without much trouble.His defenses can stilll be breached because of the corruption caused by Naraku that had weakened him (Hosenki) greatly.

Super Strength: He is powerful enough to hit Inuyasha and send him flying. After the hit Inuyasha lost consciousness for a short amount of time

Trivia

 * Hosenki's seiyu is Ōtomo Ryūzaburō, so he has the same voice as Crocodile from One Piece and Dabura from Dragon Ball.