Jin Toujou is the father of the protagonist, Basara Toujou, and a figure of legendary status within the world of heroes and demons. He is a tall, slim man of average build with disheveled brown hair, brown eyes, and glasses, and bears two large scars on his face. His typical attire consists of casual clothing, often a white shirt and grey pants, and he is frequently seen with a cigarette. He works as a freelance photographer, a profession that allows him to maintain a low profile while supporting his family.

In his past, Jin was a member of the Hero Clan and became renowned as the strongest hero ever produced, a living legend known as the War God. During the Great War between heroes and demons, he fought against and formed a complex relationship with two powerful beings: Sapphire, the sister of the Demon Lord Wilbert, and Raphaeline, one of the Ten Gods. His relationship with both women resulted in the birth of his son, Basara.

Jin's personality is defined by a stark contrast between his relaxed, carefree demeanor and a deep-seated seriousness and rebellious nature. Despite his laid-back appearance, he is a calm and careful planner who values family above all else, far more than the Hero Clan or any other organization. He is deeply protective of his son, having abandoned his duties as a hero to raise Basara without the interference of the Hero Clan's elders. His rebellious streak leads him to defy the corrupt decisions of the Vatican and the Hero Clan's leadership, choosing to follow his own feelings and protect those he loves, even if they are demons or gods. This is demonstrated when he takes in Mio Naruse and Maria Naruse, protecting them under the guise of becoming their stepfather, fully aware that they are demons targeted by the current Demon Lord's faction.

Jin's role in the story is primarily as a catalyst and a hidden guardian. He sets the main plot in motion by adopting Mio and Maria and then leaving on a business trip, entrusting his son with their protection. Despite his absence for much of the series, he remains an active behind-the-scenes player, engaging in political maneuvering within the demon realm and intervening directly during critical moments, such as confronting the Demon Lord Leohart. He acts as a mentor and source of strength for Basara, teaching him how to win in crucial battles and providing guidance.

His key relationships are central to his character. His bond with his son, Basara, is incredibly strong; he sacrificed his heroic status to save him and has immense confidence in his abilities. He feels a deep responsibility and sympathy for Mio Naruse, taking her and her servant Maria into his family to protect them. His past relationships with Sapphire and Raphaeline are the source of his family and a major motivation for his actions; he later travels to the Divine Realm to free Raphaeline from the Ten Gods, showing his wrath and willingness to defy divine beings for the sake of his family.

In terms of character development, Jin is already a fully realized and powerful figure when the story begins. His arc involves transitioning from a legendary hero in hiding to actively engaging in a larger conflict to secure peace and protect his expanding family. He fulfills the wishes of his wives to stop the conflict between heroes and demons before embarking on a personal quest to the Divine Realm.

Jin possesses formidable abilities that make him one of the strongest characters in the series. As a hero, his strength, speed, and stamina are immense, and he is a master swordsman able to match and surpass a current Demon Lord without using his full power. His true power comes from ingesting the blood of the ancient evil dragon Fafnir, which caused his soul to evolve and granted him potent draconic abilities. This power is so great that he can effortlessly defeat multiple clones of powerful enemies and even face the Ten Gods themselves, striking fear into even the most corrupted leaders of the Hero Clan.