Tsubasa, a shy, timid elementary school student, lives with his Grandma, Dad, and Mom. Tsubasa's a Grandma's boy-whenever he's feeling down, he seeks her out and confides in her. She's always willing to lend an ear and give him the reassurance he's looking for. It's okay, she says, no matter what the situation might be. When Tsubasa's getting picked on at school, Grandma saves the day. But Grandma starts changing. She asks the same questions over and over, she forgets how to be knit, something she'd been so good at. Grandma has the forgetting disease. She starts getting angry out of the blue, lets the plants in her garden dry up, eats all the jam she'd made especially for Tsubasa, and it all scares him. So much so, in fact, he starts avoiding her. One day, she got up and leaves the house without any shoes on and stays gone. Where's Grandma? Tsubasa asks, and starts to learn what's happening to the woman he's looked up to for so long.