Nagare is the current head of the Kurosaki clan, and the father of Kurosaki Hisoka. As head, it is his duty to bear the village of Kamakura's ancient god, Yatonogami, inside of his body... where it torments him physically and psychologically. It is causing him to go blind, and appears it will eventually kill him at a relatively young age. Without an heir, once Nagare dies, the fearsome god will be free to exact vengeance on the small mountain village. Earlier in his life, Nagare was married to a woman named Kasane, whom he's implied to have loved dearly. Together, they had a daughter (also named Hisoka) who was murdered by his brother Iwao. In grief, Kasane drowned herself. To cover up her death, and possibly in a deranged attempt to replace her, as suggested by Watari, Nagare married her identical twin sister, Rui, who is the second Hisoka's mother. After Hisoka was born, once he got older, empathic powers began to manifest in him. Nagare and Rui's response was to lock him away in a cell. It's worth noting in flashbacks that multiple people pleaded with Nagare to kill Hisoka, which he apparently refused to do as Hisoka died of other circumstances; the cell appears to have been a compromise to appease people who were frightened of Hisoka's powers. Nagare appears to regret how he treated his son, going so far as to say that he wishes he could "go where the [his] children are," but he doesn't have the resolve to kill himself and allow the village to be punished by Yatonogami. He currently is still wrapped up in a blood feud with Iwao, who is bitter about Nagare being the younger brother yet the one to inherit title of clan head. All information cited from the pages of the manga itself.