The Monogatari series, comprising the light novels written by Nisio Isin and its anime and manga adaptations, has an extensive fictional cast. The series focuses on Koyomi Araragi, a former vampire who has since regained his humanity and now lives as a partial human with vampiric traits, as he meets various girls who contend with other supernatural threats, collectively known as "Oddities". He is initially assisted by Meme Oshino, an eccentric specialist in the area of combatting and exorcising Oddities, and later by Shinobu Oshino (formerly known as Kiss-shot Acerola-orion Heart-under-blade), the weakened form of the vampire who attacked and turned Koyomi, who now depends exclusively on his blood for sustenance. Koyomi is also commonly accompanied by the various girls he has helped in the past. He is sometimes opposed or aided by other specialists seeking to exterminate or manipulate Oddities for their own reasons.
Main characters
Koyomi Araragi
is the overall main protagonist of the Monogatari series. He is a third-year high school student who fails every subject except math. After being attacked by a vampire during spring break and becoming a vampire himself, specialist Meme Oshino helps him become human again, though Koyomi retains several lingering side effects and vampiric powers such as enhanced regenerative abilities. As a result, he has concerns regarding his lifespan. These side effects are later revealed to be due to the bond that Shinobu and he share. He started dating Hitagi at the end of Mayoi Snail and later becomes her husband. After graduating from university, Koyomi follows his parents' footsteps and becomes a police officer.
Although he is shown to be attracted to the other girls, he turns down their advances due to his loyalty to Hitagi. Other characters, particularly Mayoi and Hitagi, seem to speculate that Koyomi is a lolicon.
Hitagi Senjōgahara
is the main character of Hitagi Crab. She is a weak-looking girl with an "incurable disease". She is in the same class as Koyomi, but she rarely speaks. During the period between both schools, she encountered a giant crab who stole her weight. Ever since, she avoids contact with everyone else, and threatens anyone who discovers her secret. She became anti-social and was very different from her personality from when she was in middle school. She calls herself a tsundere (but is mostly a yandere) and often speaks in an abusive style. At the end of Mayoi Snail, she admits that she loves Koyomi, and they start dating.
After the events in Tsukihi Phoenix, she overcame all of her trauma and finally became a completely normal and cheerful girl. She starts referring to Araragi by a cute nickname, chuckling at small things, and sending e-mails full of Emojis, although her sharp tongue is still present, only toned down. She seems also to have a father complex, getting excited when she uses her father's blanket, so much so that she can't fall asleep. Koyomi says that he loves Hitagi the most. She seems to not be on very good terms with Karen and Tsukihi.
In Hitagi End after the events of Nadeko Medusa, Koyomi gets into trouble, swallowing her pride and feelings again to ask Kaiki - the one person whom she truly despises and hates - for help.
Mayoi Hachikuji
is the main character of Mayoi Snail. She is the ghost of a fifth-grade elementary-school girl. She was killed in a traffic accident while trying to reach her mother's home and has since unsuccessfully attempted to do so. She can be seen only by people who do not want to reach their destinations. Koyomi met her in a park on Mother's Day and offered to help her find her mother's home. She makes a lot of spelling mistakes and has a habit of mispronouncing Koyomi's family name. Her family name before her parents got divorced was She later graduates to become a "Wandering Spirit," after Koyomi and Hitagi help her reach her destination.