Aspic: Majaou no Noroi (1988)

You obtained the Book of Truth, which is needed to break the curse on the princess. As you return to the king, you find that the princess is missing. Three days prior, a wizard appeared and informed the king that there was another way to save the princess, so the king entrusted the princess's life to the wizard. Now that you've returned, the king begs you to find out what's become of the wizard and the princess.