"Rennyo Monogatari" is a historical anime series set in 15th-century Japan during the Muromachi period. The narrative centers on Rennyo, a Buddhist monk and the eighth head priest of the Hongan-ji Temple, a significant institution within the Jōdo Shinshū sect of Buddhism. The story explores Rennyo's efforts to revive and expand the sect amid political turmoil, social unrest, and religious persecution.

The series begins with Rennyo inheriting the leadership of Hongan-ji after the death of his father, Zonnyo. Facing opposition from rival Buddhist sects and feudal lords, Rennyo works to unify and strengthen the Jōdo Shinshū community. His teachings emphasize the accessibility of salvation through faith in Amida Buddha, resonating with peasants and commoners who feel marginalized by the rigid class structures of the time. This populist approach attracts a growing following but also incites hostility from established religious and political powers.

As the story progresses, Rennyo faces numerous challenges, including internal dissent within the sect, external attacks on Hongan-ji, and the complexities of navigating alliances with powerful samurai clans. The series depicts his strategic relocation of the temple to safer regions, his efforts to codify teachings, and his role in fostering a sense of unity among his followers. Key historical events, such as the Ōnin War, serve as a backdrop, highlighting the broader societal upheaval of the era.

The main characters include Rennyo, portrayed as a compassionate yet determined leader; his wife, Nyoshunni, who supports him through personal and political trials; and various disciples and followers who play pivotal roles in the sect's survival and growth. Antagonists include rival monks, feudal lords, and political figures who view Rennyo's growing influence as a threat to their authority.

The series balances historical accuracy with dramatic storytelling, offering a detailed portrayal of religious reform, social change, and the struggles of leadership in a turbulent period. It provides insight into the development of Jōdo Shinshū Buddhism and its enduring impact on Japanese culture and spirituality.