Karigurashi no Arrietty

A family of little people lives under the floorboards of an old house far out in the countryside, surviving by secretly borrowing items from the humans who inhabit it.

One day, their existence is discovered by a kind young boy named Shou, who is visiting his grandmother, to find some quiet before his upcoming heart operation...

Note: Although the original novel was set in England during the 1950s, the Ghibli version takes place in present-day Japan.