Kuma’s numerous affiliations have many readers stumped on what sort of past he may have had.
His earliest depiction is of him as a child, seemingly a peasant doing manual labour. We then know he rose to become King of the Sorbet Kingdom, while being simultaneously affiliated to the Revolutionary Army as one of their commanders. After that, he became a Marine Warlord and eventually fully transformed into a mindless robot, PX-0.
In his latest appearance, he was shown to be a slave of the Celestial Dragons.
In order to rationalize this bizarre sequence of events, we must begin from Kuma’s childhood.
In Volume 63’s SBS section, child Kuma was shown along with the rest of the Warlords as kids. His design is quite telling compared to the rest of the Warlords. This is because he is carrying a bundle of sticks on his back and reading a book named “Ninokin” leading us to believe that Kuma was inspired by Ninomiya Sontoku. Sontoku was a Japanese philosopher, economist, agricultural leader and most importantly moralist. Sontoku was immortalized by his acts of kindness, specifically when he fed the starving population of Odawara, despite lacking the Shogun’s approval. I believe that Kuma did something very similar in the Sorbet Kingdom.