The game follows the tale of Chakan, a warrior who was so confident in his martial arts (especially his unmatched swordsmanship) and gifted abilities in sorcery and alchemy, that he declared even Death couldn't best him in battle. Of course, Death appeared and challenged Chakan with a proposition. If Chakan could defeat him, he'd be granted eternal life. However, if Chakan was defeated, he'd become Death's eternal servant. In another side-story, Chakan was so feared by the elders of multiple tribes, they dropped their petty differences and amassed to figure out a way to defeat or contain him, and upon overhearing his boasting, summoned the Grim Reaper themselves, informed the Reaper of his boastings, and contracted him to defeat Chakan.
The battle raged on for several days, spells and swords clashed, until the ultimate victor was very clear...Chakan. Because he defeated Death eventually, he was granted his "reward":
“You are a tactful swordsman, so I will not renege on our wager. I grant you the kiss of eternal life, but, for your arrogance and pride I will temper my gift with this curse. You will be a mere shell of yourself as I strip you of most of your powers. Each nightfall, evils will be shown to you, and the pain of their victims will be your pain. You will never know rest as you wander this world searching to slay the horrors that haunt your sleeping world. You will suffer grievous wounds, but you will not die, and as eternity rolls on, you will crave my touch. Your face will bear my visage, and your eyes will burn with hellfire. But...let it not be said that I am without mercy. There shall be an end to your curse. If all the beasts of the dark are slain, then you may find rest."
Chakan will live forever until he destroys the four supernatural evils of the terrestrial plane (Spider-Queen, Mantis, Elkenrod, and Dragonfly King) and the elemental plane (Parasite, Tundra Beast, the Last Dragon and the Leader of the Dragonfly Clan).