High school senior Daniel Larusso and his mom, Lucille, move from Newark, New Jersey to Reseda, Los Angeles, California. When they arrive, Daniel meets a neighbor named Freddy Fernandez, who invites him to a beach party taking place the next day. Their maintenance man is an eccentric but kind and humble Okinawan immigrant named Kesuke Miyagi.
At the beach party, Daniel meets Ali Mills, a high school cheerleader from Encino. The two fall for each other, which draws Johnny Lawrence's, Ali's ex-boyfriend, attention. Johnny is the top student of a karate dojo called "Cobra Kai," who attack Daniel. Johnny and his gang continue to bother and harass him. At a Halloween party, Daniel douses Johnny, leading to a chase. Daniel is eventually caught and beaten, but Mr. Miyagi arrives and rescues him and beats up the five attackers with ease. Amazed, Daniel asks Miyagi to teach him to fight. Miyagi refuses, but agrees to accompany Daniel to the Cobra Kai dojo to resolve the conflict. They meet with the sensei, John Kreese, an ex-Special Forces Vietnam veteran, who dismisses the peace offering and demands to set up a match between Daniel and the other Cobra Kai students. Miyagi proposes that Daniel should enter the Under-18 All-Valley Karate Tournament, where he can compete with all the Cobra Kai students, and request that the bullying cease while Daniel trains. Kreese agrees to the terms, but warns that if Daniel doesn't show up at the tournament, Daniel and Miyagi will become targets.
Daniel's training starts with menial chores he believes only makes him Miyagi's slave. When he becomes frustrated, it is explained that these actions have helped him learn defensive blocks through muscle memory. Their bond develops and Daniel learns about Miyagi's dual loss of his wife and son in childbirth at Manzanar internment camp while he was serving with the 442nd Infantry Regiment during World War II in Europe, where he received the Medal of Honor, the Army's highest award for valor. Through Miyagi's teaching, Daniel learns not only karate but also important life lessons such as the importance of personal balance, reflected in the principle that martial arts training is as much about training the spirit as the body. Daniel applies the life lessons that Miyagi taught him to strengthen his relationship with Ali.
At the tournament, Daniel unexpectedly reaches the semi-finals. After Johnny defeats a highly skilled opponent, Kreese instructs Bobby Brown, one of his more compassionate students and the least vicious of Daniel's tormentors, to disable Daniel with an illegal attack to the knee. Bobby reluctantly does so, getting disqualified in the process. Daniel is taken to the locker room, where the physician determines that he can't continue, but Daniel believes that if he doesn't continue, his tormentors would have gotten the best of him. So he convinces Miyagi to use a pain suppression technique so that he can continue. As Johnny is about to be declared the winner by default, Ali tells the master of ceremonies that Daniel will fight. Daniel then hobbles into the ring and faces Johnny.
The match is halted when Daniel uses a scissor leg technique to trip Johnny and deliver a blow to the back of the head, giving him a nose bleed. Kreese orders Johnny to sweep Daniel's injured leg, an unethical move. Johnny is horrified at the order, but does so under Kreese's intimidation. As the match continues, Johnny seizes Daniel's leg and delivers a vicious blow, doing further damage. Daniel, standing with difficulty, assumes the "Crane" stance, a technique he observed Miyagi performing on the beach. Johnny lunges toward Daniel, who jumps and delivers a kick to Johnny's chin, winning the tournament. Having gained respect towards his nemesis, Johnny takes Daniel's trophy from the master of ceremonies and presents it to Daniel himself as Daniel is carried off by the enthusiastic crowd.
Cast[edit]