The Demon God has abducted the princess Misa, intending to sacrifice her in order to restore his power. The king has sent an army to rescue his daughter, led by a knight who was carrying the legendary Sword of the Valiant. All the soldiers were killed by the minions of the Demon God, and only the brave knight survived. But as he delivered the fatal blow to the Demon God, he was himself mortally wounded by him. The princess Misa has no other choice but to take the Sword of the Valiant and to find a way to escape from the Demon God's dungeon, full of deadly traps and enemies...