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 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.

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.

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.

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.

Tsubasa suffers from an inexplicable headache. Koyomi rushes to meet Tsubasa at the park, and learns of her paranormal situation.

Koyomi takes Tsubasa on a visit to Meme to find out how to save her. For some reason, Meme is acting indecisively.

Meme is not himself these days, caused by Shinobu’s disappearance from the house. Koyomi, Mayoi, Suruga and Nadeko all search for Shinobu.