"Doraemon: Summer Holiday" is a short anime film that centers around Nobita Nobi and his friends as they embark on a summer adventure. The story begins with Nobita, feeling bored and unenthusiastic about his summer vacation, wishing for something exciting to happen. Doraemon, his robotic cat companion from the future, decides to use one of his futuristic gadgets to create a miniature island in Nobita's room. This island, complete with lush greenery, a beach, and a small volcano, becomes the setting for their summer escapade.

Nobita invites his friends—Shizuka, Gian, and Suneo—to join him on the island. The group enjoys various activities, such as swimming, exploring, and playing games, immersing themselves in the tropical environment. However, their fun takes an unexpected turn when they discover a mysterious egg on the island. The egg hatches into a small, dinosaur-like creature, which they name "Peko." The children quickly bond with Peko, treating it as a pet and caring for it.

As Peko grows rapidly, the group faces challenges in keeping it hidden and safe. The island's limited space and resources become a concern, prompting Doraemon to suggest relocating Peko to a more suitable environment. The friends decide to travel back in time to the Cretaceous period, using Doraemon's time machine, to find a place where Peko can thrive. This decision leads to a series of adventures as they navigate the prehistoric world, encountering various dinosaurs and natural phenomena.

The narrative explores themes of friendship, responsibility, and the importance of making difficult decisions for the well-being of others. The children must confront the reality that Peko belongs in its natural habitat, despite their attachment to it. The story concludes with a heartfelt farewell as they return Peko to the Cretaceous period, ensuring its survival and happiness.

Throughout the film, the interactions between the main characters—Nobita, Doraemon, Shizuka, Gian, and Suneo—highlight their distinct personalities and dynamics. Nobita's clumsiness and good-hearted nature, Doraemon's resourcefulness, Shizuka's kindness, Gian's boisterousness, and Suneo's vanity all contribute to the group's chemistry and the story's progression. The film balances lighthearted moments with emotional depth, creating a memorable summer adventure that resonates with audiences.