Phantom Kingdom: Portable is an enhanced port of Makai Kingdom that was released on the PSP in Japan on October 11th, 2011. The port of the game includes a new character, Petta, along with a new scenario titled "Papa is the Strongest Overlord in the Universe".

After the destruction of his Netherworld is prophesied by Pram the Oracle, Overlord Zetta travels to the Forbidden Library to prevent it. Finding the Sacred Tome, a book that controls reality, Zetta finds a passage claiming that his own stupidity would be the downfall of his Netherworld. Infuriated, he burns the book, only to remember immediately afterwards that destroying the book would destroy his world in a self-fulfilling prophecy. He quickly responds by confining his soul to the Sacred Tome and ventures to rewrite his world into existence by having the other Overlords of Netherworlds write wishes within his pages.

After fighting through a number of different Netherworlds, Zetta is supposedly fatally cursed by a godlike being known as The One. Soon after, his lost former pupil, Salome, asks him to marry her. Traveling to her Netherworld, Zetta fatally wounds Salome in battle. However, she reveals that she was already dying beforehand. The true strongest Overlord, Salome was giving all of her mana to Zetta in secret due to her unrequited love for him. Realizing this, Zetta asks Pram to revive Salome, but she is thwarted by the vengeful Overlord Seedle. Alexander defeats Seedle, but Zetta is left without hope of reviving Salome or returning to his body.

However, Trenia reveals herself to be the spirit of the Sacred Tome that was exiled from the book when Zetta put himself into it. Believing that Zetta has learned his lesson and become a more humble person, she confines herself back into the Sacred Tome, giving him back his body and full power. Zetta then proceeds to revive Salome using his immense power. Meanwhile, it is revealed that the curse of The One is fake, and that the true The One is actually Ophelia.