This episode takes place before the actual planning of the School Fair and shows how the girls spend their summer holidays.

On their way back from the 18th floor, Hestia, Bell, and the others accidentally uncover a hidden, mystical hot spring, and they decide to stop by to refresh themselves until creatures lurking in the dark appear to attack them.

Doraemon: Nobita no Takarajima takes the well-known characters to the Caribbean Sea; Nobita is the captain of a ship and fights against his enemies. Shizuka is kidnapped and a storm prevents her persecution. When the adventurers finally find the mysterious Treasure Island, where they have taken Shizuka, they discover that it is something more than a common island.

(Source: Official Website)

Nobita and his dad buy a big rhinoceros beetle, which he promises to his dad to take good care of it. Later, Doraemon's group finds a strange island where a tribe co-exists with prehistoric creatures long believed to extinct yet preserved by a mythical beetle spirit named Golden Hercules. However, the group has to deal with a group of criminals from the future who intend to capture Golden Hercules for a profit.