"Reikenzan: Hoshikuzu-tachi no Utage" is a fantasy anime series set in a world where cultivation and martial arts are central to the narrative. The story revolves around Oubu, a young boy who becomes the disciple of a mysterious and powerful cultivator named Eiko. Oubu is chosen to participate in a rigorous selection process to join the prestigious Reikenzan sect, a group of elite cultivators who train to harness spiritual energy and achieve immortality. The selection process is highly competitive, involving numerous trials that test the participants' physical, mental, and spiritual abilities.

As Oubu progresses through the trials, he encounters a diverse group of fellow candidates, each with their own unique backgrounds and motivations. Among them is Eiko, who initially appears aloof and enigmatic but gradually reveals her own connection to the Reikenzan sect and its history. The trials are designed to push the candidates to their limits, forcing them to confront their weaknesses and grow stronger. Along the way, Oubu uncovers hidden truths about the sect, including its darker aspects and the political intrigues that threaten its stability.

The narrative explores themes of perseverance, self-discovery, and the pursuit of power, as Oubu and his peers navigate the challenges of the selection process. The series delves into the complexities of the cultivation world, where alliances are fragile, and the line between friend and foe is often blurred. Oubu's journey is marked by moments of triumph and failure, as he learns to balance his ambition with the moral dilemmas posed by the sect's teachings.

The main characters include Oubu, whose determination and resourcefulness drive the story forward; Eiko, whose mysterious past and formidable skills make her a key figure in the narrative; and a supporting cast of candidates who each contribute to the unfolding drama. The series combines elements of action, humor, and introspection, creating a multifaceted portrayal of the cultivation world and the individuals who strive to master it. The plot is structured around the trials and the relationships between the characters, with a focus on their growth and the evolving dynamics within the Reikenzan sect.