Relics: Ankoku Yousai (1987)

At some point in the early history of earth, the forces of darkness known as HELL were at war with the forces of light known as HEAVEN, and the took this battle to our planet. The HELL forces quickly enslaved human beings, and the earth was cast in darkness and despair. Somewhere on the planet, a fortress was built to harness the power of the sun in order to defeat the forces of HELL, should they ever come to our planet, but it fell into ruin after centuries of neglect. The Shining Princess of HEAVEN was captured and imprisoned on the top floor of this fortress. Also inside are the spirits of the Holy Warriors of Light who have the power to defeat the forces of HELL. However, they are asleep and unable to awaken. Earth's only hope is you, a being who has sacrificed his body in order to inhabit the fallen bodies of the departed. To succeed, you must use each body to obtain the key words which are found in, and used to open, the dungeons of the fortress.