Three centuries of unseen existence have taken their toll on Jack Frost. But when the Man in the Moon chooses him as a Guardian, Jack is thrust into a world he never knew existed. Alongside the legendary figures like Santa Claus, the Easter Bunny, the Tooth Fairy, and the Sandman, Jack must confront Pitch Black, the Boogeyman, who threatens to plunge the world into fear. Yet, a mysterious figure known only as 'Halloween' or 'Samhain' holds a crucial piece of the puzzle, a spirit chosen long ago, burdened by secrets, and perhaps the key to Jack understanding his own destiny.

Forgotten by the world, two figures float through the ages, their powers shaping the seasons and the heart. Jack Frost, the spirit of winter and mischief, yearns for belief. (Y/N), known as Cupid, the embodiment of love, understands his loneliness. But as a shadow from the past threatens the very foundation of childhood wonder, they are called upon by the Man in the Moon for a destiny neither expected: becoming Guardians. Can the boy no one sees and the girl who gives what she can't have protect the children's light?