Jose is a central character who serves as a handler for the Social Welfare Agency, partnered with the young cyborg operative Henrietta. A former officer in the Carabinieri, Italy's military police, he hails from a family deeply embedded in the legal profession, with his father serving as a powerful public prosecutor and his mother as a defense attorney. This background was shattered by a terrorist car bombing that killed his parents and his younger sister, Enrica, a traumatic event that fundamentally shapes his character and his motivations for joining the agency.

In his role as a handler, Jose is distinguished by his deep-seated opposition to the agency's practice of treating the conditioned girls as mere tools for assassination. He is acutely aware of their capacity for emotion and pain, and his approach is defined by consistent kindness and endearment towards Henrietta, a stark contrast to the more detached or utilitarian attitudes of some other handlers. This compassion is driven in part by guilt, as he struggles with the ethical implications of using children in such a manner, and by a personal sense of connection; Henrietta is noted to bear a strong resemblance to his deceased younger sister, suggesting his care for her is a complex mix of genuine affection and an attempt to assuage past loss. His wish to save her, originally driven by a need he could not fully articulate, evolves into a persistent effort to provide her with a semblance of a normal life, including activities like stargazing, listening to her play the violin, and sharing simple pleasures.

Jose's personal philosophy heavily influences his professional methodology. He strives to expand Henrietta's horizons beyond weapons and tactics, teaching her to view the world through art, science, and culture. Despite this gentle hand, he maintains a clear distinction between their personal bond and their operational roles, acting as a firm but fair instructor during missions, scolding her when necessary but never allowing his anger to linger. His kindness, however, proves to be a double-edged sword. It fosters a deep, unwavering loyalty in Henrietta, who becomes fiercely protective of him, sometimes to the point of losing control and acting against orders when she perceives him to be in danger. This dynamic places Jose under constant scrutiny from his peers, particularly his older brother, Jean, who often criticizes his methods.

Jose's primary and most defining relationship is with Henrietta. He acts as her protector, teacher, and the primary object of her conditioned affection, a bond that is central to the series' narrative. His secondary significant relationship is with his brother Jean, another agency handler, with whom he shares a past marked by shared family tragedy and a present defined by their differing approaches to their duties. This shared history of loss is a key part of his background and fuels his and Jean’s vendetta against terrorism.

Throughout the story, Jose's development is characterized by his struggle to balance his humane instincts with the brutal realities of his work, a conflict that ultimately leads to tragedy. In the final arc of the manga, Jose sustains a critical gunshot wound from Henrietta while she is in a confused state. Accepting his fate, he instructs her to kill him and then herself, leading to a mutual death by pistol shots to the eye, a grim and poignant end to their partnership. Jose is a capable operative in his own right, possessing extensive knowledge of military tactics, proficiency with firearms, and the strategic acumen to train a lethal assassin, yet his notable abilities are consistently overshadowed by his profound and ultimately fatal sense of humanity.