Johann is a dhampir navigating the space between human and vampire societies, working as an information broker in Paris alongside his companions Dante and Riche. These three form a close-knit found family, with Johann exhibiting fierce protectiveness over them, especially when their safety is threatened. He occasionally supplies information about curse-bearers to Vanitas and Noé Archiviste, aiding their missions, though his actions always serve his own group's interests. Physically, Johann possesses a pale complexion, silver wavy hair, and lilac eyes. He wears rounded spectacles and is typically attired in a black suit featuring large gray lapels, a white dress shirt, a maroon tie, and red accessories including stud earrings and cufflinks. Black gloves and heeled shoes complete his outfit, and a bat often perches on his shoulder, mirroring his associates. Johann displays a flamboyant, teasing demeanor marked by animated expressions, physical affection, and a habit of wrapping his arm around others or kissing Dante during reunions. He adopts a deliberately feminine and flirtatious speech pattern, particularly in Japanese, though this cheerful façade vanishes when angered or when Dante or Riche face danger. Beneath the playful exterior lies a short temper and deep-seated rage, most evident when his "dham family" is threatened. He is highly observant, frequently analyzing others like Noé while masking his judgments behind playful interactions, such as calling Noé "darling" despite an underlying coldness. His involvement in key events highlights his loyalty and volatility. During the Parisian Excursion arc, Johann alerts Dante about Lord Ruthven's Bourreau and later chastises him for allowing Riche to pursue the dangerous vampire Thomas Berneux. In the Beast of Gévaudan arc, Johann is tasked with monitoring Noé but loses track during chaos. Separated from Dante by an avalanche, he locates a shelter where Vanitas and Jeanne rest. When Vanitas threatens Dante's life, Johann's demeanor shifts instantly from affable to lethally serious; he vows to kill Vanitas if he harms Dante, embodying his core declaration: "Meddle with my ‘family’… and I kill you". Johann's combat abilities derive from his dhampir heritage, granting enhanced speed, strength, and endurance. He employs pragmatic tools like a net gun during battles, such as when confronting Astolfo Granatum's chasseurs to protect Dante, prioritizing practicality over brute force. Unresolved elements persist regarding Johann's true allegiances and nature. During the Gévaudan incident, his unexplained absence during the Book of Vanitas's chain-severing event and subsequent isolation after the avalanche fuel speculation. A prevalent theory links him to Charlatan member Monsieur Spider, citing physical similarities and circumstantial evidence: after Noé kicks Spider in an earlier encounter, Johann reappears with a broken arm, claiming injuries from one of Moreau's reinforced humans—a story uncorroborated by witnesses. Additionally, Jeanne exhibits unusual difficulty discerning if Johann is human or vampire, reacting with visible suspicion when he identifies as a dhampir. These details, combined with Spider’s height matching Johann’s, suggest hidden connections, though this remains unconfirmed.