Shimura Wataru who was expecting his first child, but died from illness before the child was born. His wife, Nao, gave birth to the child, Ayumu, alone and five years passed. One day, Ayumu found a challenge letter inside the picture book about pirates. And so he began the adventure to search for the treasure. Nao didn't believe in the letter at first, but when she realized the letter was written by Wataru, together with Ayumu, she started to search for the treasure as well. During the search, her friends and acquaintances helped and it brings back a lot of her memories with Wataru.
Uchiyama Rina as Nao
Mukai Osamu as Wataru