Doraemon is sent back in time by Nobita Nobi's great-great grandson Sewashi to improve Nobita's circumstances so that his descendants may enjoy a better future. In the original time-line, Nobita experienced nothing but misery and misfortune manifested in the form of poor marks and grades, physical disasters, and bullying throughout his life. This culminates in the burning down of a future business he set up which leaves his family line beset with financial problems. In order to alter history and better the Nobi family's fortunes, Sewashi sent him a robot called Doraemon.
Doraemon takes out the Sonic Oscillation Terror Machine, which converts high decibel sounds into a sound wave that rids the house of pests. Nobita decides to use Gian's terrible singing and invites him over to his house to sing. Nobita later begins an exterminating company and invites Gian over to their classmates' houses to get rid of the pests with Gian's destructive voice.
Learning that teen idol Mari Marui is having a shoot at a nearby park, Doraemon and Nobita go there along with Gian, Suneo and Shizuka, but she is nowhere to be found. Mari, who is tired of her daily routine arranged by her manager mother, wishes to take a break, so she switches places with Nobita using the Substitution Bar.
Nobita, as Mari, is hesitant to go on stage to film the music segment. Mrs. Marui becomes angry with her.
Doraemon is ashamed when Nobita says he wants to be the neighborhood bully when he grows up.
A rope that can bring anything falls into Suneo's hands and he uses it to take stuff from the other kids, then Nobita gets the blame but a good deed reveals the true villain.
Doraemon and Nobita argue who is scarier, a werewolf or mom. Doraemon takes out the werewolf cream to transform himself to prove a point. Mom finds the cream and uses it before heading out to an old friend's house. Doraemon, worried, tags along to prevent mom from transforming whenever she looks at a round object.
Gian is giving Nobita trouble so Doraemon gives him a medicine which makes his words into solid letters which can be used as weapons.
Doraemon and Nobita use a TV antenna, which allows the wearer to be prepared for any event that will happen.
Nobita wishes to go to another world where Gian and Suneo won't chase him, so Doraemon gives him a Mirror World to travel into another dimension.
Nobita, Shizuka and Suneo are horrified when Gian tells them his dream is to be a food investigator and that he's going to cook them all a meal. Nobita tells Doraemon everything and he takes out the Super Gourmet Spice, which makes anything taste good.
Doraemon gives Nobita an ointment which when rubbed on the fingers, fires a jet of air powerful enough to knock someone over. Remade as "Air Pistol" in 2001.
After getting tired of Tamako's strict tyranny, Nobita uses Doraemon's Cuckoo Egg to trade places with Suneo.
Dekisugi gets an 85 on his test much to the shock of everyone else in the class. Shizuka comes to Nobita's house and explains to him and Doraemon that Dekisugi got a call from someone who's blackmailing him. Nobita and Doraemon travel several hours into the future to Dekisugi's room and use the Object Electrical Transmission Adapter to find out who the culprit is. Remade as It's Solved! The Dekisugi Case in the 2005 series.
The episode starts off with Suneo and Gian asking Nobita if he wants to go to the pool. Nobita runs away and is questioned by Doraemon. Nobita reveals that he can't swim and that they were just mocking him. Doraemon seeing that Nobita is embarrassed to go to the community pool decided to create a pool for Nobita in the sky. Along the way, Suneo, Gian, and Shizuka tag along.
Hearing that Gian will blacklist the baseball players who did poorly including him, Nobita uses the Y Candle from Doraemon to bribe his mother into returning the baseball bat and glove she had confiscated. Then he uses it to bribe Gian into letting him play.
Nobita takes four cats off of Shizuka's hands as a favor but his mother doesn't want them in the house. Doraemon uses bracelets to control them and the cats become obedient mousers in the neighborhood.