A giant demon bear named Akakabuto has taken over Futago pass. Shortly after, a silver, tiger-striped Akita pup named Gin is born and is trained as a bear-dog. Gin is brought to Riki (the leader of a large pack of dogs and Gin's father) to join the pack. Riki let's him join after proving his strenght and sends his platoons to all parts of Japan to recruit strong males to fight Akakabuto.
Gin, the third generation of bear-dogs goes through many hardships for the purpose of stopping the terrifying bear, Akakabuto.
(Source: ANN)

Shiroi Senshi Yamato was the first dog manga created by Yoshihiro Takahashi. The story was about the white akita Yamato and his life. Yamato was born with a special mark on his forehead and was to become a fighting dog. The story follows Yamato as he grows up and becomes stronger and stronger. He ends up winning the championship which was the goal for the young dog. (Source: anything-asian.net)

The sequel to Ginga Densetsu Weed, Ginga Densetsu Weed: Orion follows the story of Weed and Koyuki's puppies: Orion, Bellatrix, Rigel, and Sirius.

Gamu is a special dog belonging to the Kagero Clan of Japan in the 16th century. He is a Ganin - a dog ninja. Armed with armor and the ability to wield weapons, Gamu strives to defeat the evil Gama.

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, hopeing 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.
(source: Wikipedia)

Side stories for "Ginga Densetsu WEED"
1. The Journey of Mel
2. Lonely Ron
3. Shion's Hurricane
4. Hanako

Story of Akame's family origins dating back to the days when the conflict between Iga and Kouga started.

The story of Lassie begins with her birth in a petstore. She was raised here, but everytime she got bought by costumers, she ran back to the store. In the end, no one wanted her. One day, a young girl named Asuki is employeed at the petstore and she immidialy throws her love on Lassie. She takes the dog for walks, pet and feed her. On one of their daily walks, Asuki is being attacked by three guys who try to rape her. Lucky enough, the guys didn’t complete their goal because Lassie attacks them. Asuki is so gratefull for her rescue that she give Lassie a small pendent. She promise to come and pick up Lassie as soon as she can afford to keep a dog. A few months later Akusi calls the store, only to find out that Lassie has been sold. However, Akusi can’t buy her from the new owners since Lassie has run away from them. And thus, Lassie’s journey began.
Lassie is travelling through the mountains when she bumps into the American bulldog, Bull. Bull fights Lassie because f the human pendent she’s carrying around her neck. As they fight, the German Shepherd, Germaine enters and saves Lassie. However, he doesn’t help her further on, but tells her to take care of herself. Lassie continues her journey, but exhausted from that and the fight, she almost passes out in the nearby village. A young boy, Yakuji, finds her and takes her home for medical care. Lassie stays with him for awhile, but a few days later she sees Germaine beng hunted by Bull. She leaves the boy and fights Bull off. She then takes care of Germaine. He's badly wounded and Lassie realises that if she shall save him, he’ll need human care. She fetches Yakuji and he takes care of Germaine and gives him a new home.
Lassie then continues further down South. Here she meets the Shiba, Jiyomaru who has been forced from home by his master’s lover, Majigo. Lassie helps Jiyomaru re-unite with his owner and also with getting the evil Majigo out of Jiyomaru’s home. Alas, once more, Lassie says goodbye to a friend and continues her serach for Asuki. What she doesn’t know is that Jiyomaru’s owner, Sanosuke, has contacted the petstore Lassie originally came from. Asuki quickly leaves her possition at the job and arrives only to find out that Lassie is gone. However, Jiyomaru wants to repay Lassie, so he runs out in town to find her. He succed and Lassie is finally reunited with her true owner, Asuki.
(source: GingaSite.net)

A dog named Weed happens to hear he is the son of Gin, The great leader of Ohu, Who lead the dogs of ohu to victory in a fight against monsterous bear Akakabuto. Weed wants to find his father no matter of what. On a way to his father Weed meets many friends and enemies.
(Source: ANN)