In a near-future Japan, Christmas has faded into myth, and the birth rate has dropped so dramatically that children are now the most precious commodity. Society has artificially extended adolescence to preserve their youth, and traditional holidays, like Christmas, are a mere legend of the past. 
Sanda Kazushige, a middle-school student who unexpectedly becomes entangled in a strange and dangerous mystery, when his classmate, Fuyumura Shiori, accuses him of carrying a curse that could help find her missing friend, Ono Ichie, Sanda’s life takes a dramatic turn. Together, they embark on an incredible adventure to unravel the truth behind Ichie’s disappearance and uncover the hidden magic of Christmas itself. As they delve deeper into the mystery, the duo faces external threats and internal challenges.