Episode 4: Princess of the Lost World (亡国のプリンセス Bōkoku no Purinsesu) is the fourth episode of Mashin Sentai Kiramager. It features the debut of Darkness Megabeast Mecha Smog Jouki, White Kiramai Stone, and the leader of Yodonheim, Emperor Yodon.
The Kiramagers return to CARAT HQ after successfully defeating a Jamen monster. While there, they take in the information about the Yodon Army's recent attack and seemed to have noticed the lack of a subsequent Jyajyu creature. However, what seemed to have taken its place was a jet-black Kiramai Stone, which is floating ominously in the air. "It can't be..." Mabushina's own anxiety starts to form as she rushes to the scene with the Kiramagers. It was just then that the jet-black Kiramai Stone transforms into a locomotive-type vehicle with a strange face, and is headed straight for the Kiramagers. Then the individual who descends from within it is none other than Mabushina's uncle, and the traitor to Crystallia... now Yodonheim's Demon General Galza, who reveals his scheme to assassinate the princess to ensure her kind's permanent extinction, for she is the sole survivor of her home-planet's massacre.