It is the Taisho Period in Japan. Tanjiro, a kindhearted boy who sells charcoal for a living, finds his family slaughtered by a demon. To make matters worse, his younger sister Nezuko, the sole survivor, has been transformed into a demon herself. Though devastated by this grim reality, Tanjiro resolves to become a "demon slayer" so that he can turn his sister back into a human, and kill the demon that massacred his family.
The summer of his high school freshman year, Hodaka runs away from his remote island home to Tokyo, and quickly finds himself pushed to his financial and personal limits. The weather is unusually gloomy and rainy every day, as if taking its cue from his life. After many days of solitude, he finally finds work as a freelance writer for a mysterious occult magazine. Then, one day, Hodaka meets Hina on a busy street corner. This bright and strong-willed girl possesses a strange and wonderful ability: the power to stop the rain and clear the sky.
A spy, an assassin and a telepath come together to pose as a family, each for their own reasons, while hiding their true identities from each other.
