The Red Moon
The Red Moon is both a special ritual and a location in Disgaea: Hour of Darkness. During a Red Moon, Prinnies who have redeemed themselves by doing good deeds will be able to reincarnate and leave behind their Prinny costume. It features prominently in the episode Reincarnation, where Laharl attempts to stop Death from releasing the souls of several of his Prinnies. In the credits, Kurtis is shown journeying to the Red Moon, presumably to be allowed to go to Heaven and meet his family.
The song "Akai Tsuki" is used while the Prinnies releases their souls. While in Disgaea 2, the theme "Akai Tsuki" is played when a race is reincarnated into a prinny to "atone for their sins". "Akai Tsuki" is japanese and means "Red Moon".