There is a huge island in the middle of the wide ocean.
It is an artificial island created by the old humans who flourished in prehistoric times.
There are only a few small houses on the island, and there are no shopping malls, factory areas, or buildings.
The houses are widely spaced, and every house has a large garden, but there is hardly any sign of life.
The artificial island is almost uninhabited, and because it is maintained by various robots, the houses have kept the appearance they had when people lived there.
From one small house on such an artificial island, a girl's humming can be heard.
The girl was cooking a festive meal in the lovely kitchen of her small home.
And from time to time, the girl takes off her apron and goes for a walk to see how far the lifting of the barriers covering the man-made island has progressed.
The girl would watch the dismantling for a while, smile with satisfaction, and then go home again to start cooking a celebratory meal.
The girl creates various kinds of dishes and sweets, arranges them on pretty plates, and puts them on a small table.
When the table is filled with plates, she removes her apron and hangs it on the apron rack in the kitchen.
The girl looks in the mirror and checks the wall clock, worrying about her hair.