Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: What do they release into the shelter, for light? Title: Grave of the Fireflies Movie plot: The date is September 25, 1945, shortly after the end of World War II. A young boy sits against a pillar at Sannomiya Station, dying of starvation. Later that night, a janitor removes his body and digs through his possessions, finding nothing but a candy tin containing ashes and a few fragments of bone which he throws away into a nearby field. From the tin springs the spirit of the young boy followed by his little sister along with a cloud of fireflies. The spirit of the young boy, Seita (Tsutomu Tatsumi, English: J. Robert Spencer), narrates the story of how he and his sister, Setsuko (Ayano Shiraishi, English: Rhoda Chrosite), fared in the wake of the firebombings of Kobe during the war.14 year-old Seita and 4 year-old Setsuko live with their mother (Yoshiko Shinohara), English: Veronica Taylor) comfortably in Kobe while their father serves as a captain in the Imperial Japanese Navy. One day, air raid sirens go off as a fleet of American B-29 Superfortress bombers flies overhead. The children's mother, who suffers from a heart condition, puts Setsuko in the care of her older brother and instructs him to secure the home while she goes ahead to a bomb shelter. Hundreds of incendiary bombs are dropped on the city and most of the civilians are caught off-guard. Seita and Setsuko manage to survive the bombing unscathed and go in search of their mother. They find her at a makeshift clinic set up within a school, horribly burnt and covered head to foot with bloody bandages. She dies a short time later and is cremated in a mass grave with other casualties.Despite their loss, Seita is determined to care for Setsuko and protect her at all costs. They travel to the home of their aunt (Akemi Yamaguchi, English: Amy Jones) who allows them to stay but convinces Seita to sell his mother's kimonos for rice. While living there, Seita goes out to retrieve leftover supplies he had buried in the ground before the bombing and gives them all to his aunt, however, he keeps one tin of fruit drops for himself. The children's aunt...

fireflies