Takashi Kitaguchi (北口隆司, Kitaguchi Takashi) is a member of a yakuza organization who has been fighting with Yasukuni Shindou for succession since their previous boss' death.
Kitaguchi is a ruthless and ambitious man with a character befitting a member of the yakuza. Unlike Shindou, he gives little thought to the lives of his subordinates.
Prior to the start of the story, the head of Kitaguchi's syndicate died, and the matter of succession was left undecided between him and Shindou. While the pair struggled for leadership, Kitaguchi hired Abe and Yamamoto to kill some of his own men in order to turn the tables on his competitor.
Niwaka Samurai Impersonator Arc
Though Kitaguchi himself never makes an appearance, he is mentioned and alluded to in the story. After hiring Abe and Yamamoto, the pair watch an apartment until a group of men enter. They follow the group inside and kill all but one witness, asking him, "Where is Kitaguchi?" The question makes it appear that Shindou has sent the killers to eliminate his competition and justifies Kitaguchi's aggressive pursuit of him.
Kitaguchi hires the Niwaka Samurai to finish Shindou off in apparent revenge for the murder of his subordinates. Shindou attempts to hire the Niwaka Samurai, but Xianming Lin takes the place of his bodyguard instead. Lin sends Shindou ahead of himself during a fight, and the Niwaka Samurai kills Shindou before he can make his escape. It can be assumed after his death that Kitaguchi steps up as the next boss of their yakuza outfit.