In a small town, there was a grandfather named Backer who told stories to children every day. One day the grandpa suddenly stopped showing up, and the doctor said he had lost something. So, the children used their energy to help grandpa find that "thing" by guessing, so that grandpa could rejoice and go back to telling them stories as before. However, the doctor said that the children had not found the "thing" that the grandpa had lost. What was it, then? Perhaps the answer was in a letter …