Akakabuto is the main antagonist of Ginga Nagareboshi Gin and father of Monsoon.
Akakabuto is a very unique bear, even so that humans were not sure about his species.
One of his most distinctive traits (the one that he was named after) was the red mane running down his back. Otherwise, he is brown and originally sized similar to the brown bears of Hokkaido.
His right eye is blind, making it easier to tell him apart from his offspring.
Akakabuto is originally around 2-4 meters in height, but eventually grew into incredibly 12 meters. In the end, his weight was about 5,000 kg.
In Ginga Densetsu Riki, Akakabuto has been causing trouble by attacking and consuming the farmer's cattle and soon starts to attack humans. The hunter, Takeda Gohei starts to hunt the dangerous bear together with his dog Shiro. On a hunt, Akakabuto attacks Takeda Gohei and the other hunters causing all of them to die except Takeda Gohei who loses his left ear. Akakabuto and Shiro fight and Takeda Gohei does his best to protect his dog by shooting Akakabuto's right eye out causing him to go insane. Shiro sees no other option than to push Akakabuto and himself down a valley, Shiro dies but Akakabuto survives.
In Ginga Nagareboshi Gin, the hunt for Akakabuto has not stopped. Takeda Gohei is still hunting his death enemy to avenge Shiro and get payback for his ear. Takeda Gohei has got himself a new bear dog, Riki - the son of Shiro. Akakabuto manages to capture Takeda Gohei and Riki in a crack in a cliff. Akakabuto had wounded both Takeda Gohei and Riki. Akakabuto throws Riki into a valley as they fight but as Akakabuto is about to attack Takeda Gohei which he hate for shooting out his eye, the rescue team arrives and Akakabuto decides to flee.
Time passes and Akakabuto holds the Futago Pass in a firm grip but Gin and Daisuke do their best to fight him off. Riki, who survives the fall, has gathered a group of dogs to overpower Akakabuto and bring him to his death, Akakabuto sees no other option but to do the same. He rallied up troops of bears, and sets them on guard to protect his main fortress, Gajou.
In the final battle, Akakabuto had hid his minions in the cracks of Gajou to surprise the dogs but Riki and his pack manage to kill off Akakabuto's minions. As Akakabuto is the only bear left, he fights fiercely against the dogs which leads to many deaths, including Akatora who tears out Akakabuto's remaining eye. Riki can't afford to lose any more dogs and shows Gin the Zetsu Tenrou Battouga, they attack Akakabuto's back to cause disability of his arms. Even though Riki and Gin have used a destructive and deadly attack the monster bear refuses to die. But the dogs get help from Takeda Gohei who shoots Akakabuto once but not even that is enough, Akakabuto stands up yet again and attacks Takeda Gohei and Riki, they both get badly injured. Gin angrily uses the Battouga and slashes Akakabuto's head off, thus killing the demon bear.