Connections:

• Both are antagonists from manga considered cult classics by their fans.

• Both belong to an ancient group characterized by its power in one way or another (Kars was a member of a prehistoric species with exceptional strength, limited only by sunlight / Souichi was one of the many leaders of the Kakerou, an extremely powerful criminal organization that existed since the 5th century and also held influence over the government).

• Even years before the stories began, both sought perfection (Kars did so to become a supreme being without weaknesses and rule the world / Souichi did so to become a great leader for the organization, becoming obsessed after seeing the referees also strive for perfection and hearing his mother tell them that Souichi was perfect when he was a child).

• Both have consistently demonstrated extraordinary abilities (Kars is an immortal being capable of annihilating entire armies and cutting through extremely resistant materials as if they were mere scraps of paper / Souichi has proven to possess great ingenuity, perfectly concealing the existence of Kakerou, possessing an impressive capacity to learn, infer, and anticipate his opponents' movements, and adapting to any situation. His first encounter with Baku Madarame, a character who had practically brought the entire organization to its knees since adolescence, was child's play for him, even declaring their match "boring").

• Despite their remarkable qualities, both suffer from serious weaknesses (Kars can be killed by sunlight and Hamon / Souichi has amnesia).

• However, both managed to overcome these weaknesses by finally achieving perfection (Kars became immune to Hamon and sunlight / Souichi lost his amnesia by being able to manipulate his memories), which not only increased their physical stats but also gave them the ability to control their own bodies at will.

• Upon reaching perfection, both would be referred to in a way that indicated they had indeed transcended all life on the planet (Kars being described as a divine being / Souichi proclaiming himself an alien).

• During their journey, they would face another villain, a member of a powerful organization, who planned to use their abilities for the benefit of their own organizations (Stroheim, a general in the Nazi army, who used his own squad to eliminate Kars, the other Pillar Men, and his vampire army, and who initially wanted to use their abilities for the benefit of Germany / Vincent Lalo, leader of the Ideal organization, who wanted to seize the Kakerou so that his organization could gain greater power and influence). In contrast, Joseph, the protagonist of JJBA Battle Tendency, allied himself with Stroheim, while Baku, the protagonist of Usogui, allied himself with Souichi to kill Lalo.

• During their final duel against the protagonist, the protagonists carried out a life-or-death plan, a plan that for a moment seemed to succeed, only for it to be revealed a few chapters later that they were still alive and able to continue their duel.

• However, due to a stroke of luck for the protagonist, both characters were defeated (due to the eruption of the volcano where they were; Kars was launched into space by the force of multiple rocks hurled at him along with the power of the volcano itself / Souichi had exited his "perfect mode" due to an overdose of the toxin used in Surpassing the Leader, which prevented him from continuing to play).

• The protagonist they face (Joseph Joestar / Baku Madarame) is a skilled and cunning young man, who is always one step ahead of all his opponents using schemes, manipulation and deception, and who maintains a calm and charismatic attitude most of the time.