Nadeko Snake, Part 2
Oshino informs Koyomi that Nadeko is under the effects of a Snake Constrictor, a snake spirit that slowly constricts the life out of its victim. Nadeko explains that it is a curse a classmate placed on her after Nadeko inadvertently rejected the confession of a boy the classmate liked. Normally, a curse placed by an amateur would be harmless, but Nadeko accidentally made the curse worse by performing her ritual at the shrine, which has been corrupted by Shinobu's presence. Koyomi obtains a special charm that will banish the Snake Constrictor and they return to the shrine. While the ritual is seemingly successful, Koyomi realizes that Nadeko is under the attack of two Snake Constrictors, the second being placed by the rejected boy. While the first one is banished, Koyomi is forced to battle the second to keep it from killing Nadeko. He and Kanbaru manage to chase it off, but Koyomi feels guilty for not being able to destroy it, as the Snake Constrictor will return to the person who originally placed the curse.
Aired 11/09/2009EP 10 - Nadeko Snake, Part 2

Bakemonogatari
First season of the Monogatari Series, part 1/6. Contains the arcs Hitagi Crab, Mayoi Snail, Suruga Monkey, Nadeko Snake, and Tsubasa Cat from the Bakemonogatari light novels.
Thanks to Meme Oshino, Koyomi Araragi, a high school student, is able to remain a human after coming across a female vampire... However, since the incident, Koyomi seems to meet girls who have an apparition-related issue. Hitagi Senjougahara doesn’t weigh anything, Suruga Kanbaru’s right arm becomes like that of a monkey’s, and a young girl, Mayoi, cannot find her way home no matter how many times she tries. Koyomi, a Mr. Nice Guy, ends up helping each and every girl solve her problem with the help of Meme Oshino.
(Source: Aniplex)
Note: Only the first 12 episodes were broadcast on television; the remaining three episodes were distributed on the anime's website between November 3, 2009, and June 25, 2010.