Byakuya Ishigami, an astronaut aboard the International Space Station, witnessed a global petrification event turn every human on Earth to stone. Before this cataclysm, he balanced life as a part-time professor with his astronaut dream, conquering his inability to swim through encouragement and experimental suit designs from his adoptive son, Senku Ishigami. Though not Senku's biological parent, Byakuya adopted him when the child's parents could no longer provide, even selling his car to fund Senku's early scientific pursuits. Stranded in orbit, Byakuya coordinated with fellow astronauts Connie Lee, Shamil Volkov, Yakov, Darya, and celebrity Lillian Weinberg for their return to Earth. After landing, he swam ten kilometers through treacherous seas to rescue stranded crew, ultimately relocating them to an uninhabited island. Recognizing the astronauts as humanity's sole survivors, Byakuya resolved to build a society to aid Senku's future revival. He established a settlement on this island—later known as Treasure Island—and spearheaded efforts to preserve crucial knowledge and resources. Over the following years, pneumonia and accidents claimed the lives of Byakuya's crew, leaving only him and Lillian. He meticulously documented survival techniques and ethical principles in "The Hundred Tales," a collection of stories passed down through generations. The final tale held a personal message for Senku, revealing that the promised "souvenirs" from his space mission had evolved into future allies for Senku's scientific revival. Anticipating resource scarcity, Byakuya also collected rare metals like platinum, safeguarding them within the Soyuz spacecraft capsule alongside glass records containing the astronauts' messages and songs. In his final years, Byakuya continued mentoring the descendants of the original crew. He died of old age while panning for metals in a stream, collapsing as he gazed at the stars mirrored in the water, his last thoughts fixed on Senku. His legacy endured through Ishigami Village in Japan, founded by his descendants, and the guiding wisdom of the Hundred Tales millennia later. The rare metals proved vital for producing revival fluid, while the tales concealed coded messages pinpointing resource locations and revealing the petrification beam's origin in South America.