Ginga Nagareboshi Gin anime

Father of Gin, mate of Fuji and a hunting dog belonging to Takeda Gohei. He was trained by his master and very faithful until he was thrown off a cliff by Akakabuto. He lived the fall but forgot his past. The only thing he remembered was the desire to defeat that evil bear so he gathered a goup of soldiers and gained respect by his comrades. When Gin meets him for the first time as a pack member he calls the leader 'father'. This sparks an interest in Riki and he wonders why he can't remember his past from over half a year ago... He sends the Platoons in his army across Japan to gather more warriors with the time allowed: three moons.
  He stays behind to keep an eye on the twin pass. Riki gains scars from battles with the bears that Akakabuto has join him in defending the fortress that he is building. When the army returns he is very proud of his soldiers for gathering many strong males for the fight. He also heard great things about Gin. On the day of battle against Akakabuto, he tells Ben to stay with Cross and her puppies. As the rest of his pack is attacking Akakabuto's allies in waves, Riki sets off on his own and climbs up the cliff behind the rock castle in hopes of getting Akakabuto alone. He gets ambushed however and thrown down in a ditch with trees thrown on top of him. Luckily he survives and regains his memory prior to being thrown off the cliff.
  He shows up late, but he is still able to command his men in the fight with Akakabuto. Riki lets Gin know he is his son and he passes down the bearhound fighting technique, the Zetsu Tenrou Battouga. Gin and Riki disable Akakabuto by hitting crucial points in the back. The demonic bear till rises then falls after getting shot after beign shot by Takeda Gohei's rifle. While the army cheers because they think Akakabuto is dead, he crushes Riki between his paws. Gin decapitates the bear with the battouga and Riki proclaims gin as the new leader. As the sun comes out of the clouds, Riki passes away leaving his legacy to Gin.

Ginga Densetsu Riki

Riki is also a main character of a short manga called Ginga Densetsu Riki, tellling about Riki's puphood before he began training as a bearhound. He was born a runt and wasn't even considered as a potential barhound, but upon meeting his father Shiro, Riki is determined to become strong like Shiro.