Nobita is in Shizuka's house, raving about a TV series that he saw, with Shizuka showing disinterest and telling him that she doesn't watch those kinds of shows. Nobita then asks if she heard a song that he heard lately. Just then Suneo calls out to Shizuka and invites her to see a microscope that his father brought. Nobita intervenes by saying Shizuka is playing with him, however Suneo insists that playing with Nobita must be boring for her and states that the microscope can look at the plankton with more detail. Nobita then states that Shizuka won't come since she's not interested in seeing a microscope, however Shizuka expresses her interest, much to his dismay.
At the empty lot, Nobita seethes about Suneo and swears to upstage him as he takes a rock and throws it. The rock hits Gian who just arrived at the empty lot and thinking that Nobita threw it on purpose, chases him and beats him up. Nobita arrives into his room sobbing, and Doraemon asks him to stop crying and tell what happened. Nobita explains the whole situation to Doraemon, to which Doraemon states that it's his fault for acting like a child and being jealous. Distraught, Nobita states that he wishes for a friend who would stand by him, get angry whenever he gets angry, and be loyal to him. In response, Doraemon brings out the robot pet dog named Chukenper. He explains that the dog will be extremely loyal to its master just like the dog who's statue is in Shibuya, and once he activates it and it looks at Nobita in the eyes, he will become its master. Chukenper is activated and runs around Nobita affectionately, while Doraemon states that the gadget won't help him in the long run. When asked why, Doraemon states that Nobita needs to study, takes less naps and read more books. Nobita is annoyed with Doraemon's lecturing and so is Chukenper who turns on him and chases him out of his room. Nobita is delighted to have a loyal pet and decides to take a nap to which Chukenper brings out his futon so that he can sleep confortably. As Nobita takes his nap, Tamako arrives, scolds Nobita for being lazy and ask him to go out for a shopping errand. This infuriates Chukenper who chases Tamako away and bites her skirt, while Nobita tries to make it let her go. In the chaos, Nobita takes the basket and tells his mom that he'll do the errands and runs off with Chukenper following him.
While sitting under a tree in the empty lot, a relieved Nobita asks Chukenper to go to the store and get the groceries. However, Chukenper returns and gets chocolate and caramel candies instead. Nobita ties Chukenper to a tree and tells him to stay there while he goes back home and apologizes to his mother. Tamako is less than pleased with Nobita not bringing the groceries and cancels his lunch as punishment. Nobita dejectedly returns back to the empty lot, blames Chukenper for his predicament and is about to leave. But upon seeing Chukenper sad, he has a change of heart and decides to allow it to accompany him. They go to the park where they meet Suneo and asks him what he's doing. Suneo smugly states it's not something he can understand which angers Chukenper. Nobita introduces the pet dog to Suneo and advises him not to insult him otherwise it will attack. Suneo then explains that he's fishing for plankton, which Nobita figures it's so that Suneo can use his microscope. Nobita wishes that he could see Suneo's microscope which prompts Chukenper to leave and bring the microscope to Nobita, causing him to flee the park before Suneo finds out what he did. After getting away, Nobita assures Chukenper that he's not upset with it and then a baseball hits his head, which belongs to Gian. Gian apologizes for throwing the ball at him and Nobita assures it's alright and throws it back to him. This causes Gian to suspect that Nobita is acting strangely and he grabs his collar, thinking he's planning something. Chukenper then lunges at Gian and thrashes him. Nobita pleads for it to stop and runs, thinking that Chukenper is causing a lot more problems to him than necessary. However, Chukenper refuses to leave Nobita's side, leaving Nobita amazed and horrified.
Just then, Shizuka walks by and when Nobita asks her where she's going, she states she's going to Dekisugi's house to do homework with him. As Shizuka leaves, Nobita is a bit disappointed that Shizuka wants to go to Dekisugi's house and Chukenper, seeing Nobita's desire, follows Shizuka and drags her by the skirt to him. Nobita frantically tries to deny any involvement, however Shizuka smacks him in the face and angrily walks off, stating she never wants to see Nobita's face ever again. Distraught that Shizuka hates him, Nobita bemoans that he wants to die, which prompts Chukenper to bring some rope so that he can hang himself. Meanwhile, Doraemon searches for Nobita and finds him in the empty lot, with Chukenper trying to force Nobita to hang himself. Nobita cries for Doraemon to help him and after a stylish jump, Doraemon pushes the button to deactivate Chukenper. Nobita thanks Doraemon for his help while Doraemon sighs with relief stating nothing good came out of this experience. The episode ends with the frame focusing on a deactivated Chukenper.
The dog statue in Shibuya that Doraemon references during his explanation of the Robot Pet Dog gadget to Nobita is a reference to the dog Hachikō, who is a Japanese Akita dog known for his loyalty to his owner Hidesaburō Ueno. He's held up in Japanese culture as an example of loyalty and fidelity and is referenced in popular culture through statues, books, movies, and various other media.
In the 1979 anime, Chukenper's color is green whereas in the 2005 anime, its color is brown.