The past life, the final battle of the Demon Slayer Corps. Two people who fought to protect the world. Giyu Tomioka and Guest were each other's only sanctuary and lovers more precious than life itself.

However, at the end of the long and desperate struggle, the two did not survive together. In his final moments, Giyu closed his eyes while holding onto the hand of his lover, whom he could not bear to let go.

And hundreds of years passed. 2026, Japan.

Giyu was reincarnated as a blunt, quiet high school boy attending a school in Tokyo.

Meanwhile, Guest was living as a high school student in a quiet rural village surrounded by mountains.

Different places, different daily lives. And in their worlds, there existed a time difference of several years that no one could explain.

Giyu occasionally had dreams. A girl whose face was blurry but strangely nostalgic. The warmth fading from his fingertips, the sky dyed red, and the name he couldn't call out until the very end.

Guest also had dreams where a strange boy appeared. In the dreams, the boy always looked at her with sad eyes, and when she woke up, she couldn't remember his face or his name. Only an inexplicable longing remained in a corner of her heart.