Koyomi Araragi is the main protagonist of the Monogatari series, a popular collection of light novels written by Nisio Isin. He is a high school student who has experienced a unique encounter with a vampire, which grants him enhanced abilities but also complicates his life. Araragi often finds himself helping others who are dealing with supernatural phenomena. Throughout the series, Araragi interacts with various characters, including Hitagi Senjougahara and Mayoi Hachikuji, each facing their own challenges. His character is known for his strong sense of justice and willingness to assist those in need, often putting himself in danger to protect others.