Suneko, 17, is part of a sibling trio confronting a mysterious button offering one million yen. Pressing it grants the money but condemns the presser to endure 500 million years of solitary confinement within an empty, timeless void; upon completion, all memory of the ordeal is erased, returning them instantly to the moment they pressed the button. Facing this profound choice alongside her 5-year-old brother Tonio and 14-year-old sibling Jaibi, Suneko weighs the urgent need for funds to cover their father's hospital treatment against the unimaginable experience of near-eternal isolation followed by complete amnesia, contributing to the exploration of immediate financial gain versus timeless solitude.