Doji was one of the main antagonists of the anime and manga series, Beyblade: Metal Fusion. He was an enemy of Gingka and the former leader of Dark Nebula who had Ryuga. He used to own Dark Wolf DF145FS. Doji seeked the power of the "Forbidden Bey", Lightning L-Drago 100HF. As revealed in "Beyblade: Metal Fury", he was one of the bladers who worshipped the evil god of destruction and planned to bring him back all along.
Doji and Ryuga would not give up and started to wear a long coat that covered himself, a top hat, an artificial leg, and a walking cane due to the attack he suffered at the hands of L-Drago. As a result, he found Rago and the Nemesis Bladers and brought them to Pluto as he made his ultimate return in Beyblade: Metal Fury, only to die once again due to Ryuga's new Special Move.
Doji finally returned in the Shogun Steel anime in A New War, but this time, he was apparently revived by Merci. He was converted to life energy stored within the Hades computer system. His new form poses as a threat to the WBBA and the future of beyblading.
Doji is a person who never really gets serious even if his enemies were strong such as Gingka. He is also a person who doesn't like to show his real power, especially not to children. Doji is extremely cruel, often punishing members of the Dark Nebula by "feeding" their power to Lightning L-Drago 100HF. He is never one to give up on his goals and desires, as he uses his intellect to get ahead of his enemies. He always speaks in a polite manner, even to his enemies, but there's no mistaking the arrogance in what he says. He'll frequented access people as 'my friend' in a condescending manner. Generally, he appears to never accept people as being on his level.
As shown in Metal Fury, Doji has a habit of taunting those who oppose him. In episode 141, he even goes so far to anger Ryuga by making note of him helping Gingka, as well as degrading him to a mere pawn in Hades Inc's plan. It's a form of manipulatoin, as he clears knows this will cause Ryuga to immediately stop any cooperation with the other Legendary Bladers. Doji appears to take great enjoying of taunting Ryuga, as he laughs hysterically at the Dragon Emperor's reaction (which also reveals him to be more psychotic than before). He has even done this to Gingka back in Metal Fusion when he "awakened" Lightning L-Drago.
Socially, Doji keeps his distance (Yu was the only one who had the potential to form a friendship with him.) He only associates with those who can be of use to him. Pwerful bladers like Ryuga deserve the upmost of respect, in his mind. Although Doji doesn't get close to others, he has the ability to "play others emotions like a piano". This shown in episode 3 of Metal Fusion when he agitates Kyoya to the point where he bets on his free will. He also does this in Metal Fury to Ryuga in order to mess up Zues's Barrier.
In private, he has a conflicted relation with his own interests. He claims to 'hate cacti so much that he can't think about anything else'. The ture reason for this, as Doji further describes, is that they are so prickly that he can't hug them. This sort of utter obsession with things he can't have seems to be a large part of his character motivation. In the anime version of Shogun Steel, he is especially driven by this - given he is physically dead, he can't have any form of physical sensation which he now misses terribly.