In Japanese mythology, Yomi is the underworld in which horrible creatures guard the exits. According to Shinto mythology as related in Kojiki, this is where the dead go to dwell and apparently rot indefinitely. Once one has eaten at the hearth of Yomi it is impossible to return to the land of the living. Yomi is comparable to Hades or hell. This realm of the dead seems to have geographical continuity with this world and certainly cannot be thought of as a paradise to which one would aspire, nor can it appropriately be described as a hell in which one suffers retribution for past deeds; rather, all deceased carry on a gloomy and shadowy existence in perpetuity regardless of their behavior in life. Many scholars believe that the image of Yomi was derived from ancient Japanese tombs in which corpses were left for some time to decompose. After the arrival of Buddhism, Yomi also became one of the Buddhist hells in Japan, like Kakuri which is ruled by Enma (Judge of the Underworld).
The kanji (Chinese characters) that are sometimes used to transcribe Yomi actually refer to the mythological Chinese realm of the dead called Huángquán, which appears in Chinese texts as early as the eighth century BCE. This dark and vaguely-defined realm was believed to be located beneath the earth, but it was not until the Han Dynasty that the Chinese had a clearly articulated conception of an underworld below in contrast with a heavenly realm above. With regard to Japanese mythology, Yomi is generally taken by commentators to lie beneath the earth and is part of a triad of locations discussed in Kojiki: Takamahara ("high heavenly plain", located in the sky), Ashihara-no-Nakatsukuni ("central land of reed plains", located on earth?), and Yomo-tsu-kuni ("Land of the Yomi", located underground).
Yomi is ruled over by Izanami no Mikoto, the Grand Deity of Yomi. According to Kojiki, the entrance to Yomi lies in Izumo province and was sealed off by Izanagi upon his flight from Yomi, at which time he permanently blocked the entrance by placing a massive boulder at the base of the slope that leads to Yomi. Upon his return to Ashihara-no-Nakatsukuni, Izanagi noted that Yomi is a "polluted land". This opinion reflects the traditional Shinto association between death and pollution.