"Ginga Densetsu Riki" is a manga series that serves as a prequel to the popular "Ginga Nagareboshi Gin" and "Ginga Densetsu Weed" series. The story is set in the Japanese mountains and follows the life of Riki, a powerful Akita Inu who becomes the leader of the Ōu Army, a group of dogs dedicated to protecting their homeland from threats. The narrative begins with Riki as a young pup, born into a lineage of strong and respected dogs. His father, Shiro, is a legendary figure among the mountain dogs, and Riki grows up with the expectation of living up to his father's legacy.

As Riki matures, he faces numerous challenges that test his strength, courage, and leadership abilities. The Ōu Army is formed in response to the growing threat of bears and other predators that endanger the lives of both dogs and humans in the region. Riki's journey is marked by intense battles, alliances with other dogs, and the gradual development of his skills as a warrior and leader. His determination to protect his pack and uphold his father's honor drives much of the plot.

Key characters include Riki's siblings, his loyal comrades, and formidable adversaries. Among them is Akame, a ninja dog who becomes one of Riki's closest allies, and Benizakura, a fierce and independent dog whose rivalry with Riki evolves into mutual respect. The series also explores themes of loyalty, sacrifice, and the bonds of family and friendship, as Riki and his companions face life-threatening situations and moral dilemmas.

The narrative is structured around episodic conflicts, with each arc focusing on a specific threat or challenge that Riki and the Ōu Army must overcome. These conflicts often culminate in large-scale battles, showcasing the strategic and physical prowess of the characters. The series also delves into the backstories of various characters, providing depth to their motivations and relationships.

"Ginga Densetsu Riki" is characterized by its action-packed sequences, emotional storytelling, and exploration of the natural world from the perspective of its canine protagonists. The series builds a rich mythology around the Ōu Army and its legacy, setting the stage for the events of the subsequent "Ginga" series. Through Riki's journey, the manga examines the qualities of a true leader and the enduring spirit of those who fight to protect what they hold dear.