Gilbert, known as the Holy Spearman, serves as the vice-captain of the royal knights who protect the Kingdom of Clays. He is a warrior who has reached such an extraordinary level of power that he finds himself bored and suffering from burnout, tired of achieving victory after victory with no one able to stand against him. The only person he acknowledges as being able to match his skill is his master, Sig.

Driven by a deep desire to find a worthy opponent, Gilbert one day encounters the adventurer Noor and challenges him to a mock duel out of simple curiosity. To his utter shock, he discovers that he cannot land a single attack on Noor, no matter how hard he tries. Even more striking, Noor never attempts to fight back or counterattack, despite having ample opportunity to do so. This experience leaves a deep impression on Gilbert, forcing him to realize his own immaturity and that he still has much to learn. Consequently, he comes to view Noor as his rival.

In his role within the story, Gilbert serves as an early test for Noor's abilities and represents a character whose overwhelming strength has become a source of weakness and disconnection, providing a contrast to the protagonist's obliviousness to his own power. His key relationship is with his master Sig, his only perceived equal before meeting Noor, and his newly forged rivalry with the protagonist. Through this rivalry, Gilbert begins to develop from a bored and stagnant fighter into someone inspired to continue training and improving himself. As the vice-captain of the Spearman Corps, his notable abilities are formidable enough to defeat almost everyone in a single blow, a strength that ironically leads to his immense burnout and isolation.