Oshino Ōgi

Koyomi created the "Unknown." It is an existence that can be called "Koyomi Araragi himself," a manifestation of his own self-criticism towards his feelings of inferiority, guilt, and deceit. Izuko called it "Dark Koyomin," similar to Tsubasa's Black Hanekawa and Nadeko's Kuchinawa.

The first Oddity Killer drained energy from Suruga's left hand, and after Oshino devoured this first Oddity Killer, the "Unknown" factor flowed into Koyomi, who was paired with Oshino, through the monkey's paw. Born from these circumstances, it acquired the abilities of the "bad things" contained by the armored warrior and Oshino's material creation skills, using them to expel specialists from the town and create the ruins of a burned-down cram school and the former classroom of Naoetsu High School.

Due to its origins, the "Oshino" in "Oshino Ōgi" is derived not from "Oshino Meme" but from "Oshino Ougi," as explained by Izuko (she also speculated that calling herself Meme's sister in August might have been bad publicity).

In the final scene at the ruins of the cram school she created, Koyomi, who could not abandon her, saved her just as she was about to be erased by the "darkness" after he uncovered her true identity.

Furthermore, she was defined as "my cute niece" by Oshino Meme himself, who arrived just in time with Tsubasa. This redefined her not as the Oddity "Oshino Ōgi" but as "Oshino Meme's niece," thus removing her from the target of the "darkness" and narrowly escaping death.