Godō Kusanagi is a sixteen-year-old high school student who becomes the central figure in a world of divine conflict, though he never asked for such a role. His background is that of an ordinary Japanese teenager who once had a promising career in baseball, having played as a representative of Japan in international tournaments during middle school. However, a significant shoulder injury forced him to retire from the sport, and he later discovers that his status as a god-slayer has healed this injury, though he chooses not to return to baseball. His home life involves being raised mainly by his grandparents, Ichirō and Chiyo Kusanagi, as his parents were often absent due to their careers and eventually divorced.

Godō's life takes an extraordinary turn when, on an errand for his grandfather to deliver a stone tablet in Sardinia, he becomes entangled in a battle between a great knight and the Persian god of victory, Verethragna. Through a combination of circumstance and courage, he manages to defeat this Heretic God, thereby becoming a Campione, or god-slayer, the seventh and youngest of his kind. This event grants him the divine Authorities of Verethragna, a set of ten powerful abilities known as the Ten Incarnations.

His personality is defined by a strong desire for normalcy. Despite his immense power and status as a king among magic-users, Godō consistently wishes to avoid the supernatural and live a quiet, ordinary life. He is often shy, particularly around women, and claims to be a pacifist. However, this self-image is contradicted by his actions; when a situation demands it, he shows great courage and a willingness to fight, even displaying a hidden enjoyment for battling powerful foes. He is also a combat pragmatist, using clever tactics and exploiting his enemies' weaknesses to secure victory rather than relying solely on brute force. Unintentionally, he is a major chick-magnet, attracting the affection of numerous women due to his kind nature and specific social graces taught to him by his grandfather, who was a notorious ladies' man in his youth.

Godō's primary motivation shifts over time from simply wanting to escape his responsibilities to accepting his role as a protector. Initially, he hates dealing with magic and dealing with gods and his fellow Campione, finding it a nuisance that disrupts his daily life. However, as he builds relationships with the people around him, he grows to understand that his power is necessary to protect them from the threats posed by Heretic Gods and other magical dangers. He resolves to gain the strength needed to safeguard the lives of those who care for him before fully accepting their romantic feelings.

In the story, his role is that of an unintentional hero and a king who commands the loyalty of various magic organizations and powerful individuals. He is the central figure around whom the plot revolves, as his actions as a Campione cause ripples throughout the magical world and frequently lead to the destruction of famous landmarks and historical sites during his battles. His method of fighting is unique; to activate his most powerful ability, the Warrior, which manifests as a golden sword that can cut through a god's divine power, he must have complete knowledge of his opponent's legend and nature. This information is often imparted to him through a magical kiss from one of his companions, as a Campione's body rejects external magic.

His key relationships are primarily with the four main heroines who vie for his affection. Erica Blandelli, an Italian witch from the Copper-Black Cross organization, is his first and most assertive companion, declaring herself to be his wife and often taking charge of situations. Yuri Mariya, a shrine maiden from the History Compilation Committee in Japan, provides him with spiritual support and knowledge. Liliana Kranjčar, a knight from the Bronze-Black Cross, is another skilled magic user who becomes part of his group. Ena Seishūin, a powerful sword-wielding shrine maiden, was initially sent to form a political marriage with him but genuinely falls in love with him after witnessing his battle prowess. Despite the rivalry and competition among these women, Godou cares for each of them, and they form a complex family unit around him, working together to support their king.

Godō's development throughout the series is from a reluctant and oblivious teenager into a more decisive and powerful leader. He gradually stops running from his identity as a Campione and begins to understand the weight of his position. He acknowledges the feelings of the women around him and takes responsibility for their safety, learning to use his powers more effectively and acquiring new ones, such as the legendary sword Ame no Murakumo no Tsurugi, or Grasscutter, which becomes another significant divine weapon in his arsenal. His personality deepens as he becomes more aware of his own hidden desires and strength, such as when he is freed from a curse that reveals his true, bolder nature, showing he enjoys the thrill of battle and the company of his harem more than he lets on.

Godō's notable abilities are derived almost entirely from the Authorities he stole from Verethragna, a set of powers that embody ten different incarnations or forms. Each incarnation has a specific activation condition and grants a unique power, and generally, each can only be used once per day. The Bull grants tremendous physical strength, effective against foes with superhuman power. The White Stallion unleashes a spear of sunlight that descends from the sky. The Camel enhances his combat abilities, leg strength, and defense. The Boar summons a gigantic, rampaging spirit boar to trample enemies. The Raptor (or Bird) grants him incredible speed and reduces his weight. The Ram provides a powerful healing factor that can even resurrect him from death once per day. The Goat gives him control over lightning and immense magical power, though it drains the life force of people nearby. The Youth (or Young Man) allows him to bestow the power of a divine beast onto another human. The Wind allows him to instantly teleport to the location of anyone who calls his name. The Warrior is his most tactical ability, manifesting a golden sword that can nullify a god's divine powers and authorities, provided Godō possesses sufficient oral knowledge about the god's legend and weaknesses. Later in his development, he also obtains the Ame no Murakumo no Tsurugi, a divine sword that grants him additional abilities, including the creation of a powerful black blade known as the Sword of the Beginning and the End.