Suneko, aged 17, is one of three siblings confronted by the dilemma of the 500 Million Year Button. She shares this critical family situation with her younger brother Tonio (age 5) and sister Jaibi (age 14). Their father lies critically ill in the hospital, creating significant financial strain from mounting medical bills. This urgent need for money to cover his treatment serves as the primary motivation for Suneko and her siblings considering pressing the button.

The button promises a substantial financial reward of one million yen (approximately US$7,415) to anyone who presses it, coupled with the condition of enduring 500 million years of complete isolation within an empty, timeless void. After this immense period passes, the individual's memory of the experience is erased, returning them to the exact moment they pressed the button with no subjective recollection of the elapsed time. This scenario forces Suneko and her siblings to grapple with profound philosophical and ethical questions about sacrifice, the nature of existence, and the value of lived experience versus forgotten suffering.

No concrete information exists regarding Suneko's individual actions, specific reactions to the button's consequences, personal background beyond her familial role, or distinct character development in any official media extensions.