Hosenki (宝仙鬼, "takara sen oni") is an oyster-demon who cultivates a variety of magical jewels.
Hosenki
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.