A sudden "dimensional fusion event" caused the earth to overlap with the Kamen Rider universe and the Armor Warrior universe, and the "Symbiosis Era" officially opened. The streets flashed with the red light of Kamen Rider Kuuga's battle, and the city sky echoed with the summoning sound of the armored warrior Flame Dragon Man. While the two camps joined forces to fight against the "chaos forces" spawned by dimensional fusion and the classic villains of their respective universes (the remnants of the Shadow Emperor, the Card Repair Organization), there were hidden frictions due to differences in concepts (the knights believed in "breakthrough of individual will," and the armor adhered to the "team bonding mission").
Lin Chen, a 20-year-old college student, was originally a fan of both Kamen Rider and Armor Warrior. However, after waking up, his ancestral "Light and Shadow Crystal Pendant" was activated by dimensional energy, and accidentally became the sole summoner of the Emperor's Armor, the ultimate combat power of the Armor Warrior series. Faced with this sudden ultimate power, he went from being confused and out of control at first, being questioned by the two camps, to gradually learning to control the power, and balancing the conflict of ideas between knights and armors in battles: he learned the persistence of "guarding the smile" from Kamen Rider Kuuga, understood the weight of "team bonds" with Yanlong Xia Xinnan, and used the power of light and shadow of the emperor's armor to break the barriers of "camp opposition".
From repelling the first awakening of the low-level chaos beast "Shadow Eclipse Beast", to going deep into the dimensional rift to reveal the truth of the fusion incident; from joining forces to thwart the conspiracy of internal careerists, to forming the "Symbiosis Guardian Alliance" to establish a cross-camp defense line; and finally facing the ultimate threat of the Shadow Emperor, the Shuka leader and the "Dimensional Devourer", with "faith"
