Bakemonogatari EP1 - Hitagi Crab, Part One

Koyomi Araragi catches Hitagi Senjogahara as she falls down from a great height, and he immediately notices that Hitagi weighs little to nothing; however he does not mention this to her. Later he asks Tsubasa Hanekawa, the class chairman, about her; he finds that she was sick and contemplates if that is actually the case. As he is leaving, Hitagi confronts him, as she threatens him she explains that a crab took her weight. When he agrees to keep quiet about her secret, she staples the inside of his mouth and proceeds to leave. Koyomi follows her and tells her that he may be able to help, to stop Hitagi attacking him he shows her that the wound in his mouth, inflicted a few minutes previous, had already healed. They go to see Meme Oshino, who after hearing her situation explains that it was the weight crab (おもし蟹 omoshi kani), a god, that took her weight.