Doubutsu Takarajima

Jim and his friend Gran, a mouse, run an inn together. A stranger stops by and leaves a map that leads to a treasure on an island. Inspired, they leave the inn and set sail in a small boat to pursue their dreams. They are not the only ones after the treasure, as they encounter Captain Silver and a group of pirates. Jim, Gran, and a new companion named Kathy join the race to find the treasure.