It is the prequel of both Ginga Nagareboshi Gin and Ginga Densetsu Weed. The manga tells the story of Riki, Gin's father and leader of the pack of dogs in Ginga Nagareboshi Gin. It primarily explains how he became strong and courageous, as well as his relationship with his parents. It also shows much about his father, Shiro, and of his death wherein afterward, Riki seeks revenge.
Riki, the grandfather of Weed and father of Gin, was born a runt. He was fathered by Shiro and mothered by Yamabuki. Shiro's owner, Gohei, pays no attention to Riki when he comes to pick a pup from the litter. Instead, Riki is never rehomed and becomes close to his mother. Unfortunately, Yamabuki's true owner, who had been sick, was healthy enough to take her back. She didn't feel she could handle two dogs, and decided that he would not take Riki in. Riki severely missed his mother, and one day set out to meet her. On his way, he is attacked by a pack of dogs. Hopelessly outnumbered, Riki tries to escape and falls into a river. Waking up, he learns that his father, Shiro, has rescued him. Riki had never seen his father, but had known his name. Shiro, on the other hand, didn't know that Riki was his son and left before Riki could say anything. But, not before giving him a speech on being strong. Riki makes it his goal and constantly tries to get stronger.
One day, a child named Daisuke takes a toy car (one children can ride in) through a roaded mountain pass with an incline. Riki, while traveling to see his mother, notices him racing down. A truck, not seeing Daisuke, hits the boy and sends him flying over the road railing. Afraid that he is dead, the driver moves on. Daisuke, although only bruised, is knocked out. Riki jumps onto a ledge and howls, hoping someone would hear. Instead, the pack that attacked him heard him and came. After being abused, the pack came to hate humans and attacked Daisuke. Riki, in an effort to save him, fought against the dogs and succeeded in winning. Gohei and Shiro eventually showed up, and the pack ran off. Shiro finally found out that Riki was his son.
Gohei, Shiro, and a few others head out to fight Akakabuto. Seeing this, Riki follows the van. Gohei intends to kill Akakabuto, but the bear is too strong. Gohei shot the bear in the eye, and the bullet became lodged in the beast's brain. This made him go insane and, while biting Shiro, fall over a cliff. Riki witnessed all this, and was distraught when his father fell. These events set the stage for the future series, Ginga Nagareboshi Gin.
- A male red and white Akita Inu and the runt of the litter. Nobody believed him to ever amount to anything, and gave him the nickname, "little mistake". Riki's brothers and sisters were all bought by the villagers, but the runt was never adopted. He is named Riki, which means strong. He plans revenge on Akakabuto after his father, Shiro, is killed.
- Riki's father, a silver and grey Akita Inu. Shiro is the mate of Yamabuki, who gave birth to his offspring. He later realizes that Riki is his son. Shiro tells Riki to be strong and brave, which inspires him to do so. Shiro is eventually killed by Akakabuto, leaving Riki wanting revenge.
- Riki's stern and loving mother, a white Akita Inu, who belongs to "Big Sister". Yamabuki is the mate of Shiro, the legendary bear-hound. The two are separated when Yamabuki's original owner, Big Sister, wants her back. As much to Riki's dismay, Yamabuki tells him to brace himself for the future and to build up his character. Riki visits Yamabuki every day as he exercises.
- Heiji lives in the forest with his "brothers" and confronts Riki. He smells humans on Riki, and attacks him since he hates the scent. Months later after Riki had run off, Heiji and the others hear Riki howling for help, and they find the boy, Daisuke, unconscious after being hit by a truck. They attack, but Riki saves Daisuke and breaks one of Heiji's ribs. Shiro and Gohei appear, and Heiji's group run off with him. Heiji swears he'll make someone pay for his unhealing rib, but he never meets Riki again.
- Monta is Heiji's "brother" and attacks Riki with him. In the second fight, he is suffocated almost to death by Riki's grasp on his neck. He and the group leave Riki alone after they learn he is the son of Shiro.
- Gureko is one of Heiji's "brothers".
- Heiji's other brother
- The last of Heiji's "brothers" who never receives a name.
- A large, mad bear attacking local livestock and terrorizing the people of Ōu.
- Gohei Takeda
- Professional bear hunter a village in Ōu. He is Shiro's owner, Riki's owner in Ginga Nagareboshi Gin, and Gin's temporary trainer and master in Ginga Nagareboshi Gin.
- A young boy who is saved by Riki from Heiji and the stray dogs. He stars in Ginga Nagareboshi Gin as the twelve-year old who is Gin's owner. He is also a minor character in Ginga Nagareboshi Gin's sequel, Ginga Densetsu Weed, as a young man who hunts with his older friend, Hidetoshi.
- The temporary owner of Yamabuki, Riki's mother. He's taking care of Yamabuki for his sick sister. He is married to Eiko and has a son named Tōru.
- Yūjirō's wife and Tōru's mother.
- Son of Yūjirō and Eiko who feeds Yamabuki and her new pups.
- "Big Sister"
- Name unknown. The real owner of Yamabuki. She was sick, but when she is healed, Yamabuki is returned to her, much to Riki's dismay.
Ginga Densetsu Riki was originally serialized in Japan in the monthly magazine, Weed World. In March 2003, the chapters were published in a single volume under Nihonbungeisha's Nichibun Comics label. In November 2007, Nihonbungeisha released a new edition of the volume.