Even in modern-day Reiwa Japan, many girls still run away from home over minor issues, and Erina is a typical runaway who left after a fight with her mother. While helplessly spending time in a rainy park, she's approached by a strange adult man who at first seems like a savior. But he's actually a dirty old man with a lolita complex, and Erina quickly falls into his clutches, her body easily turned into his plaything... This incident is no mere coincidence, but a malicious conspiracy exploiting the girl's vulnerability.