Hare, an extraterrestrial observer, arrives on Earth to monitor human behavior. After accidentally colliding with human Amano Inori, Hare attempts bodily repairs but inadvertently enhances her physique. These modifications grant Amano heightened intelligence, athletic prowess, and a dramatically enlarged bust. Hare then concentrates all monitoring efforts exclusively on Amano, deeming the study of this single subject sufficient to fulfill the original mission.

Initially maintaining passive observation, Hare intervenes when Amano exhibits sexual arousal toward another human named Sugiuchi. Hare actively seizes control of Amano's body to initiate and facilitate a sexual encounter between her and Sugiuchi.