Reikon, in Shinto

Shinto

or Shintoism, also kami-no-michi, is the indigenous spirituality of Japan and the Japanese people. It is a set of practices, to be carried out diligently, to establish a connection between present day Japan and its ancient past. Shinto practices were first recorded and codified in the written...

 and Japanese Buddhism, is the equivalent to the soul

Soul

A soul in certain spiritual, philosophical, and psychological traditions is the incorporeal essence of a person or living thing or object. Many philosophical and spiritual systems teach that humans have souls, and others teach that all living things and even inanimate objects have souls. The...

 or 'spirit' in western culture. When a person dies in an unexpected, violent or traumatic way, the Reikon
remains amongst the living in the people's world as a ghost who must complete an unfinished duty amongst the living. In Shinto beliefs a ghost is called a Yurei

Yurei

are figures in Japanese folklore, analogous to Western legends of ghosts. The name consists of two kanji, 幽 , meaning "faint" or "dim" and 霊 , meaning "soul" or "spirit." Alternative names include 亡霊 meaning ruined or departed spirit, 死霊 meaning dead spirit, or the more encompassing 妖怪 or お化け...

.

Sources

• http://www.nt2099.com/OSA/text/misc/GHOST.JPN
• http://www.mangajin.com/mangajin/samplemj/ghosts/ghosts.htm