Souichiro Takagi (高城壮一郎, Takagi Souichirō) is the Don of the Tokonosu prefecture's ultra-nationalist organization and a strong leader, even after the outbreak, and he will do whatever he can to keep Japanese society from collapsing. He is the husband of Yuriko Takagi and the father of Saya Takagi.
Souichiro is the Don of a right-wing political association of Tokonosu and he is a very wealthy man. His leadership skills are very strong and he serves as an example for Takashi Komuro while the group is at the Takagi house. He truly wants what is best for the city, shown by his decision to take responsibility of the water and electricity, but he has a hard time conveying this to the people since they are strongly opposed to his political views.
Souichirou is a tall and intimidating man with jet black hair and fierce orange eyes that has gaze of a predatory animal.
Souichiro has a harsh and dark outward appearance, but he is not really as ruthless when he first appears as he genuinely cares about the safety and well-being of the citizens and society of Tokonosu, though he doesn't seem to show it. Overall, he has a personality perfectly fit for a leadership role. He understands that things must always be done which will preserve that which is most important.
Not much is known about Souichiro's early life, but he is the leader of an ultra-nationalist political right wing group where Yuriko Takagi fell in love with him because of his charisma and leadership skills. He is highly-trained in swordsmanship and in the ways of the samurai that he was trained by Saeko Busujima's father.
According to Yuriko Takagi, once the outbreak started, Souichiro decided to take matters into his own hands and sent troops to the water and power plants, rather than wait for the the prime minister's orders and he also allowed survivors to take shelter at his estate. It is also shown that Saya Takagi hates her father more than her mother because he didn't ensure her safety when the outbreak started in Japan. However, this changes when Takashi Komuro reminds her of how grateful she should be that at least her parents are still alive.
He is first seen returning to his estate along with his men, having left earlier to aid survivors, during which one of his subordinates and retainers, Tetsutarou Doi, was bitten by "them" while protecting one of his comrades and became one of "them". After returning to his estate, he has a forklift carry a caged Tetsutarou to where he is. After telling the survivors about Tetsutarou and how became one of "Them" and that he is no longer human, he then decapitates the former retainer. He then tells the survivors that this is current world they are living in and that they must not hold back when fighting against "them", even if they were people they once knew.
Later on, he, along with Yuriko, approach Kohta Hirano while his men are demanding that Kohta give up his weapons. After introducing himself, he asks Kohta why he wishes to keep his weapons, Takashi Komuro, who Souchiro recognizes as Saya's childhood friend, appears and says that Kohta is able to protect his daughter. Afterwards, the other members of Takashi's group, including Saya, arrive to support Kohta, with Saya telling her father that if it wasn't for Kohta, she would have already become one of "them". It is implied that he was impressed by their willingness to challenge him and allows Kohta to maintain the weapons he took from Rika's house. Shortly after, he speaks with Saeko Busujima and presents her with one his swords, the Murata-tou, as a gift in order to thank her for protecting his daughter and to repay Saeko's father for training him.
It is currently shown that he and his followers are preparing to leave the estate in two days time and he is told by Takashi if he and his friends are not back with their parents by then, they should leave without waiting for them. He is later present when Rei Miyamoto confronts Koichi Shido, who, along with his students, had just arrived at the estate, and prepares to kill him for what he and his father did to her father. Seeing this, Souichiro allows Rei to go through with her revenge. When Rei decides not to kill Shido and walks back into the mansion, Souichiro asks her if she is certain of her decision, to which she coldly replies that Shido is not worth killing. Souichiro then orders Shido to leave the estate and to take his students with him, realizing that they have been infected by Shido's evil.
Shortly after, when an electromagnetic pulse released by a nuclear explosion shuts down all electronic devices in the city, Souichiro, having heard Saya explain what just happened, asks her if they can fix it. Saya tells him they may be able to replace some of the fried parts or find older cars without electronic parts that may work. Souichiro then praises his daughter for remaining calm and rational during the crisis. Their conversation is cut short, however, when a man runs through the gate saying that the barrier has failed, and "they" have reached the gate. Souichiro quickly calls for the gates to be closed. "They" soon break through the gates, and a battle ensues, during which a fire is started and much of the Takagi estate burns. The group and all of the remaining survivors retreat to the mansion. Souichiro decides they will fight their way to the neighbor's house, and Saya suggests they just barricade themselves in the house. He tells her there would be no point since they would still break in. He then tells Takashi and his group to leave and tells Kohta to take care of Saya. Saya tells her parents that she loves them before they attempt their escape. Souichiro and his wife were last seen fighting against the horde with rest of the estate survivors while saying that they were proud of their daughter and the friends she made. Their fate is currently unknown as his wife and him were fighting off "them".