Happily married to Koichi, 30-year-old Kaoru's world is shaken when she is diagnosed with Alzheimer's Disease. Amidst this turmoil, they discover that Kaoru is pregnant. Deciding to keep the baby, they name their little girl Himawari. But Kaoru's condition worsens, and she begins to wonder what is left that she can do...for her husband and her daughter. Before she is no longer able, she begins to write a long letter to her daughter. Her heartfelt letter forms the backbone and narration of this touching drama series.