One day, Jiro Moriyama , the main character of the story, picks up a pigeon that has fallen from the sky. It was not just any pigeon, but a famous one, Great Pigeon, owned by Kuroda Kanbei , with an anklet engraved with the letters "0666 ". Jiro desperately takes care of Great, who was weakened by diphtheria, and as a result, Great survives. Kuroda gave Jiro one of the Great's children to thank him, and Jiro participated in the pigeon race with his partner Arashi wearing the anklet of "0777", and through various events and encounters, he became a pigeon racer. They will grow together.
This is the story of friendship between people who love racing pigeons and pigeons flying in the sky.

(slightly edited MTL of description from japanese wiki)