"Scared Rider Xechs" is set in a world where humanity faces an existential threat from interdimensional beings known as the Nightfly O'Note. These creatures emerge from a parallel dimension called Blue World, seeking to destroy the Red World, the human realm. To combat this threat, the military organization known as ALCA (Alternate Life Conservation Agency) recruits young individuals with unique abilities to pilot advanced mecha units called Riders. These Riders form teams, or "Units," to defend humanity.

The story centers on Unit Blue, a group of six Riders stationed on the island of Okinawa. The protagonist, Akira Asagi, is a reluctant recruit who joins the team after being coerced by ALCA. Akira possesses a rare ability called the "Scared Rider Xechs" power, which allows him to synchronize with his Rider at an extraordinary level. However, his initial lack of motivation and emotional detachment create tension within the group. The other members of Unit Blue include Yoh Kazuki, the confident and hot-headed leader; Takt Fujishiro, the calm and analytical strategist; Akio Fudou, the cheerful and supportive medic; Hayato Akashi, the stoic and disciplined fighter; and Souichi Suganuma, the enigmatic and mysterious member with a hidden agenda.

As the series progresses, Unit Blue faces escalating threats from the Nightfly O'Note, who grow stronger and more cunning with each attack. The Riders must not only battle these enemies but also confront their own personal struggles and insecurities. Akira's journey is particularly central, as he gradually learns to trust his teammates and embrace his role as a protector. The series explores themes of camaraderie, sacrifice, and the weight of responsibility, as the Riders grapple with the emotional toll of their mission.

The narrative also delves into the origins of the Nightfly O'Note and the connection between the Red and Blue Worlds. It is revealed that the conflict between the two dimensions is rooted in a tragic history, with the Nightfly O'Note driven by a desire for vengeance. This backstory adds depth to the series, as the Riders are forced to question the morality of their actions and the possibility of coexistence with their enemies.

"Scared Rider Xechs" combines action, drama, and science fiction elements, with a focus on character development and interpersonal dynamics. The series balances intense mecha battles with quieter, introspective moments, creating a narrative that is both engaging and emotionally resonant. The relationships between the members of Unit Blue evolve over time, as they learn to rely on one another and confront their shared destiny. The story builds toward a climactic confrontation that tests their resolve and forces them to make difficult choices, ultimately shaping the fate of both worlds.