Grief

In Japanese mythology, the ghosts of ancient warriors or nobles (as well as members of the imperial house) who died a terrible, painful death and then returned to haunt their enemies.

Their revenge often takes the form of fires, wars, epidemics, droughts, floods, hurricanes, the death of members of the imperial family and other disasters that the ancient nobility regarded as curses. Since ghosts cannot be killed, the only way to end their anger is to turn them into peaceful, benevolent spirits. This was done with the help of priests and ommyo:ji using rituals called grief: shinko: — the religion of ghosts.​‌‌​‌‌​