In the third season of the Monogatari Series, the storyline delves into the Yotsugi Doll arc from the Tsukimonogatari light novel. During a winter day in February, Koyomi Araragi, while preparing for his college entrance exam, finds himself in a peculiar situation when bathing with his younger sister, Tsukihi. This event follows the resolution of the Nadeko Sengoku incident, discreetly handled by Deishu Kaiki. As Koyomi becomes aware of a significant change in his body, he turns to Shinobu Oshino for guidance, eventually reaching out to Yozuru Kagenui and Yotsugi Ononoki. The mysterious alteration prompts questions of whether it signifies a form of retribution for Koyomi's past actions. The narrative unfolds as Koyomi grapples with the implications of this unsettling development.