Godai Tamako (13), is in the first year of junior high school, living a very ordinary life with her loving parents and grandmother. The story begins one day, when her grandfather, Kenzo (68), returns home after spending 13 years in prison.

At first Tamako is unsure what to make of Kenzo, whose behavior is out of synch with the times, but - witnessing him step in to resolve a bullying incident, and seeing the obvious affection of the townspeople for Kenzo's upright manner - she gradually opens her heart to him. Then, one day, Kenzo is summoned by the boss of the yakuza (mob) that controls the town. . .