One day, a boy just sees black and white in the sky. A girl just sees black and white on the ground. It means that they just see all things with black and white outside of their home. Why do they just see the 2 colors? They can just see bright colors in the artificial things,such as clothes, comics, books, toys and etc... all things surrounding them are made by human, not by nature.
The laments of nature sometimes exist. But they are completely rot away. Sometimes, they are dead branches and stones. The most of Children seem to be pale, not with bright pink ore red on their cheeks. The food they eat are also not fresh.
One day, they open the book, called " the 20th century's dictionary". When the boy turns a page, many colors spilled out from other pages of the book. They become delighted with bright various colors, he smiled with vivid motion and colors of creatures which used to live in 20th century or before.
They also can see the beautiful shape and colors of the earth, it is the view from the space. Suddenly, the colors disappear from the dictionary. And a drid-up forest prevailed in his field of view.
You can imagine why this world lost the colors at the end of the world. At the end of the world, children do not know the concept of "colors".