A little backstory on that girl before she started school reveals that her mom had been suffering from a lung tumor that eventually develops into full on cancer. She spends approximately 7 months visiting a doctor, and doing everything she could to slow the infection down. Eventually her treatment gets too expensive to keep paying (she says that one month of treatment could feed the girl for an entire year) and she checks out of the hospital, deciding to live out the rest of her time with her daughter at home. The night before the girl starts school, her mom succumbs to the cancer, and her daughter tries to finish that 1000 paper crane challenge before that to save her, ultimately running out of time for both