Ep 1. OUGI Formula, Parts 1 & 2

In Owarimonogatari Season 1 Episode 1, titled "OUGI Formula, Parts 1 & 2", we are introduced to the main protagonist, Koyomi Araragi. The episode begins with Koyomi in his room, studying for his college entrance exams. As he tries to focus on his studies, he can't help but feel like something is off. He begins to hear a strange noise outside his window that he can't quite identify. When he looks out, he sees a figure standing on top of the roof of the adjacent building.

Koyomi goes outside to investigate but finds that the figure is nowhere to be seen. He assumes that he must have imagined it and goes back to his studies. However, the strange feeling persists, and he starts to hear more strange noises and begins to feel like he's being watched.

As Koyomi goes about his day, he runs into his friend, Tsubasa Hanekawa, who has a problem of her own. Tsubasa tells Koyomi that she has been sleepwalking and can't remember anything that happened during her episodes. She asks Koyomi for his help in trying to figure out what is going on.

The two decide to investigate together and end up at their high school, where they come across a strange blonde girl named Ougi Oshino. Ougi seems to know more than she lets on, and her presence only adds to the sense of unease that Koyomi and Tsubasa are feeling.

As the day goes on, Koyomi begins to piece together clues that lead him to believe that something sinister is going on. He recalls a legend about a demon that comes out at night and preys on humans, and starts to suspect that this might be the cause of Tsubasa's sleepwalking and the weird feelings he's been experiencing.

In the second half of the episode, Koyomi decides to take matters into his own hands and confronts the demon himself. He finds himself face-to-face with a giant, shadowy creature that resembles a man with an octopus head. Koyomi tries to fight it off but quickly realizes that he's no match for the powerful demon.

As he's about to be defeated, he hears Tsubasa's voice calling out to him. Her voice gives him the strength to keep fighting, and he manages to weaken the demon enough for Tsubasa to finish it off with a special charm that she had been given by her family.

With the demon defeated, Koyomi and Tsubasa are finally able to rest easy and go to sleep knowing that they had succeeded in protecting their town from harm. However, the ending of the episode leaves us with a sense of foreboding, as we see Ougi Oshino silently watching the two of them from a distance.

Overall, this episode sets up an intriguing and mysterious world, introducing us to fascinating characters and suggesting that there is more to the story than meets the eye.