Natsumi Kawai wants to become a photographer. She takes a bike which her late father left behind and goes to a forest to find a firefly she saw with her father. In the forest, Natsumi Kawai meets old mother Yasu and old son Jizo. They run a general store. Natsumi Kawai learns how to live in nature from them. She has happy summer days there. One day, Jizo tells her that he became estranged from his son in the past.