Blue Exorcist follows the story of Rin Okumura, a teenager who discovers that he is the son of Satan and has inherited demonic powers. After his adoptive father is killed by Satan, Rin decides to become an exorcist in order to defeat his father and protect the world. His blue hair is a symbol of his demonic heritage and serves as a constant reminder of the struggle he faces. "Blue Exorcist"
In Tokyo Ghoul, the main character Kaneki Ken is transformed into a half-human, half-ghoul hybrid after a failed surgery. Ghouls are creatures that resemble humans but feed on human flesh. Kaneki's hair turns a vibrant blue after his transformation, signifying his change and struggle to maintain his humanity while also satisfying his newfound ghoul hunger. "Tokyo Ghoul"
In Seraph of the End, a virus wipes out most of humanity and vampires emerge as the dominant species. The main character, Yuichiro Hyakuya, joins a vampire extermination unit and is given a powerful weapon that turns his hair blue when activated. This blue hair serves as a visual representation of Yuichiro's determination to protect his friends and defeat the vampires. "Seraph of the End"
Dance in the Vampire Bund tells the story of Mina Tepes, a powerful vampire who creates a sanctuary for her kind in Japan. She is accompanied by Akira Kaburagi, a human with special abilities and blue hair. Akira's blue hair signifies his connection to Mina and his role as her protector. "Dance in the Vampire Bund"
In Blood Lad, Staz Charlie Blood is a powerful vampire who becomes fascinated with the human world. He meets Fuyumi Yanagi, a human girl who is transformed into a ghost, and decides to help her return to her human form. Staz's blue hair sets him apart from other vampires and reflects his quirky personality and love for the human world. "Blood Lad"
Kizumonogatari is the prequel to the popular Monogatari series, following the story of Koyomi Araragi before he becomes a vampire. After being attacked by a vampire, Koyomi's hair turns a deep blue as a result of his transformation. This blue hair serves as a physical representation of his inner turmoil and struggle to come to terms with his new identity. "Kizumonogatari"
In Hellsing, Alucard is a powerful vampire who works for the Hellsing Organization, an agency that fights supernatural threats. His hair is a striking shade of blue, representing his otherworldly nature and immense power. It also serves as a contrast to the red eyes and dark aesthetic often associated with vampires. "Hellsing"
Strike the Blood follows the story of Kojou Akatsuki, a high school student who becomes the Fourth Progenitor, one of the most powerful vampires in existence. His hair turns a deep blue when he uses his vampire powers, highlighting his supernatural abilities and the danger he poses as a powerful vampire. "Strike the Blood"
Vampire Knight takes place at Cross Academy, a school for both humans and vampires. The main character, Yuki Cross, is a human who was saved by a vampire named Kaname Kuran as a child. In order to protect Yuki, Kaname gives her a powerful weapon that turns her hair blue when activated. This blue hair serves as a symbol of Yuki's connection to the vampire world and her role as a protector of humans and vampires alike. "Vampire Knight"
Trinity Blood is set in a post-apocalyptic world where vampires and humans coexist. The main character, Abel Nightroad, is a Crusnik, a vampire with special abilities and a thirst for human blood. His hair turns a vibrant blue when he activates his powers, serving as a warning to his enemies and a reminder of the constant struggle between his human and vampire sides. "Trinity Blood"