He is an otaku who loves his sister very much, often bailing her out when she is caught with manga at school. He has blue eyes just like Olivia.
In chapter 77 it's revealed that he lived abroad for many years, encountering numerous vampires who died painfully after drinking his blood. When one of these vampires curses Olivia to die, her brother gives the Primal Vampire his "beauty" in exchange for her life, leading to his current familiar overweight and unkempt appearance. After returning to Japan, he notes that his eyes have also become sensitive to light and wears sunglasses even indoors.
