He serves as the health teacher and psychological counselor at Star-Torch Academy. Unlike a typical school nurse, he possesses the skills to perform major surgery and refers to himself as a doctor rather than a teacher. He feels a strong sense of responsibility as a physician. Being highly competent, he is frequently called away for business trips and enjoys deep trust from the students. Although his official title is health teacher, he maintains contact with Lucilla, the academy's principal, and occasionally carries out Tacet Discord investigations or secret missions. He has blonde hair and red eyes; when using his Resonance Skill, a golden DNA-shaped pattern appears horizontally in his pupils. His hair is medium-length and always styled in a half-up ponytail. Despite his youthful appearance, he is actually in his 40s or 50s, a fact known to very few. While his hair is primarily gold, the tips are a minty green. He wears a single black ring piercing in the cartilage of his left ear. As a side effect of long-term Resonance Ability use and Ichor experiments, he suffers from color blindness where everything except the color gold appears in shades of gray. He harbors a deep hatred for the Fractsidus because he lost his father to them, and the leader of the Fractsidus once impersonated his father. Luke had a younger brother named Ray Hershel. Ray reached the brink of death after failing to endure the Ichor experiments, but Luke sealed him beneath the ice fields, keeping him technically alive. Luke, Ray, and their father are not biologically related; the father adopted the two boys because they showed high resilience during experiments. Luke has previously infiltrated the Fractsidus. He wears non-prescription glasses as a disguise when tracking or investigating them. During the period immediately after losing Ray while hunting the Fractsidus, he was stiff and rarely smiled, but his personality has since softened. His current temperament is gentle, warm, cheerful, and easygoing. He enjoys handing out candies to students and teachers, believing that sweets help stabilize and comfort the mind. In truth, this habit stems from the fact that Ray loved candy as a child. He enjoys candy himself as well. On his right palm, he bears a Stigma and a wound that never heals, from which Ichor flows. Luke's blood is hot and dangerous to ordinary people. He can extract the golden Ichor flowing from his palm to manifest weapons or other physical objects. As a child, Luke suffered from a rare disease and underwent biological experimentation disguised as treatment using Ichor. While countless subjects died, Luke was the unique case where the Ichor successfully bonded with his body, making him a Resonator. It appears Luke barely survived only because he resonated with the Ichor; given the high mortality rate caused by the Academy's experiments, the actual completion level of the Ichor was likely crude.