Shun Asanaga is a 15‑year‑old junior high student with an upbeat and lively spirit, living in his quiet hometown. One afternoon, he discovers a strange crystal glowing faintly inside his father"s laboratory, where the scientist also runs a small business. When Shun touches it, reality warps dramatically and he is transported to the mysterious realm of Endra. Emilio, a prince in that kingdom, approaches his 16th birthday and harbors deep hatred toward the reigning monarch, King Delzain. Now eligible to inherit the throne, Emilio arms himself with a sword and seeks vengeance against his uncle. Yet his power is insufficient; Delzain captures him swiftly and imprisons him in a high cell. While Emilio mourns, the prison wall distorts ominously, and Shun emerges with two aims: return home safely and finish Emilio"s revenge. What destiny awaits these two youths as they endure Endra, each raised in distinct worlds, in the shadowed valleys of ancient lore?