After the protagonist of the previous game retrieved the precious Heart of Phantasm, he was teleported away from the magical world he had been stranded in - but not to his home, as he hoped, but to another fantasy realm, Elderein. This land suffers under the yoke of the evil Prince of Darkness, and it’s up to the hero to deal with him and find a way to leave this world.
Mugen no Shinzō II is a role-playing game very similar visually and gameplay-wise to early Ultima games. As opposed to the first game, overworld occupies the majority of the screen, and towns can be physically explored in a top-down fashion. Another change is elimination of random enemy encounters in favor of enemies visibly roaming the overworld. Characters can now join the protagonist and participate in battles. Battles are viewed from first-person perspective (with large enemy portraits) and feature simple turn-based mechanics.