One day, 11-year-old Kaede suddenly collapses during class. After tests, she is diagnosed with acute myeloid leukemia, beginning a long and painful battle with the disease. Chemotherapy and radiation therapy are nothing but harsh for young Kaede, but her only emotional support is Yoshi, who is battling the same disease in the bed next to her. Around the same time, IT company owner Kengo Yanai loses his beloved daughter to leukemia. As a business owner, Kengo has no choice but to prioritize his work, but the loss of his daughter sends his once happy family spiraling into disintegration. Having lost his family, Kengo's only pride in life is that he became a bone marrow donor.