High school senior Koyomi Araragi discovers a shocking secret one day after helping his classmate Hitagi Senjougahara—a secret he is never to tell.
Koyomi takes Hitagi to consult Meme Oshino, the wandering expert on supernatural oddities. Meme provides advice to them on exorcising apparitions.
Uncomfortable after quarreling with his sister on Mother’s Day, Koyomi leaves the house. Hitagi bumps into him at the park and makes an offer.
Koyomi and Hitagi meet a girl named Mayoi Hachikuji in the park. She seems to be lost and cannot find her way home. The two try to help her.
An apparition is behind why Mayoi is unable to reach her mother’s house. Receiving advice from Meme, Hitagi tells Koyomi the surprising truth.
On his way to Hitagi's house, Koyomi bumps in to Suruga Kanbaru, the school's basketball star and an old friend of Hitagi, of whom he can't get rid of. Later that day, Koyomi is attacked by a mysterious being.
The day after his attack, Koyomi goes to see Suruga, where she tells him something about herself he can't quite grasp.
Koyomi takes Suruga to see Oshino in order to help her. However, the help he offers isn't the help Koyomi wanted...
Tasked by Meme, Koyomi heads to a lonely temple to attach a prayer slip. There he sees a dead snake that has been severed into five parts.
Koyomi taps into Meme’s powers in order to lift the snake’s curse from Nadeko Sengoku, a mysterious girl he encounters at the temple.
Nadeko comes to thank Koyomi, and the two geek out over a shared interest. Tsubasa Hanekawa passes by and suddenly complains of an acute headache.