500,000,000-nen Button

The 500 million year button. Press that button and a million yen will come out. In exchange, you have to spend 500 million years in a completely empty space. However, the moment 500 million years have passed, your memory will be erased and you'll be right back where you started. For the person who pressed the button, it would be like a million yen in an instant.

5-year-old Tonio, 14-year-old Jaibi, and 17-year-old Suneko, were at a loss for money to pay for their father's treatment in the hospital. But then, in front of the three siblings, a person with the "500 million year" button appears...