While trying to put his spelling bee trophy next to Jack's gymnastics trophy in the school hallway, Milton falls off the ladder, but is caught by a custodian, who is later discovered to be Yoshi Nakamura, a former sumo wrestler. After Milton asks if Nakamura can show him and his friends his celebration stomp move, Principal Burke is upset and fires Nakamura after Milton does a terrible job at defending him. Sad that he was fired, Nakamura hangs out at the dojo, but Jack is insistent on getting Nakamura back in the ring by training him and holding a match at the dojo. Rudy gets Yamazaki to sumo wrestle with Nakamura, but it is discovered that Yamazaki is the sumo wrestler who Nakamura lost to, scaring him and causing him to run into Rudy's office. Upset that it is his fault that Nakamura was fired, Milton attempts to take on Yamazaki himself, which does not go very well. However, this gives Nakamura the strength and confidence to sumo wrestle Yamazaki and he takes over for Milton and ends up winning the match.
A series of mysterious pranks are being pulled on the Wasabi Warriors. When Milton slides too far on a cafeteria tray in the school hallway and crashes, it is discovered that grease had been put on it; when Jerry is taking a shower at the dojo, he uses a shampoo bottle that is actually pink hair dye and freaks out. Later, while Kim and her cheerleaders are getting students pepped up for the basketball team, Kim gets stuck on the basketball banner when she tries to run and break through it. Finally, when Jack notices that Heather, a girl that he likes, is reading the note that he left at her locker and is starting to walk over toward him, he has Milton and Jerry spruce him up by spraying deodorant on his armpits and delinting him. He then finishes it off by applying a splash of cologne; however, he discovers that someone has put blue cheese in it, a smell that he cannot stand which causes him to vomit on Heather's shoes. Everyone who has been pranked suspects Truman, an obnoxious student whose father controls the mall's security cameras, to be behind the pranks; however, they discover that Eddie has been pulling the pranks. They also discover that Truman has been blackmailing Eddie to pull these pranks after the mall cameras captured Eddie practicing for the school dance. In order to help him, Jack, Milton, Jerry, and Kim sneak into Truman's father's office to retrieve the flash drive the video file is on, which they successfully do. The next morning, when Truman shows up at the dojo and confronts the Wasabi Warriors about the stolen flash drive, they show Truman an embarrassing video of himself freaking out, but state they will not post it because they are not like him. Jack then tells Truman that both videos should be deleted and he should stop messing with them, to which he agrees.
Jerry signs himself and the others up for the Battle of the Dance Crews competition, but the others are only skilled in karate and are not that great at dancing, so Jerry must train them; however, he gets annoyed when they appear to be showing no signs of improvement. Later, at Falafel Phil's, Jerry and Smooth are talking about the dance competition, and Smooth offers Jerry to be a part of his dance crew, the Step Brotherz, which Jerry accepts. The others come in and are upset to discover that Jerry has bailed on them. Later, while training for the competition, things go awry when Jerry discovers that Smooth was just using him and stole his special dance move. Later, at Falafel Phil's, when the others realize that dancing is Jerry's thing, they agree to rejoin him and take part in the competition. While Jerry's friends may not be great at dancing, they are great at karate and use that in their performance at the competition, and Jerry finishes off the performance with a new special move he worked on. While the Step Brotherz end up winning the trophy and $1,000 prize, Jerry also ends up winning a trophy for best individual dancer, which upsets Smooth, who tries to one-up him, but ends up slipping and falling off the stage.
Frank threatens to crash the mall's annual Halloween Boo-Stravaganza and Jack tells him that he better not try anything, because when he does, it usually does not go well. Later, when a clown shows up in the mall courtyard and offers Jack a coupon for Circus Burger, Jack freaks out and goes running into the dojo. Unfortunately, not only do Milton and Kim see this freakout, but so does Frank, who starts scheming to scare Jack. Milton and Kim then discover Jack's fear of clowns and learn that the fear stems from his fifth birthday party not going exactly as planned. Later, the Black Dragons show up and crash the Halloween party dressed up as clowns, which scares Jack, who runs and hides in the dojo; however, after a pep talk from Milton, Jack gets the idea to blindfold himself and use his other senses to fight the Black Dragons. Everything goes well until Frank unmasks Jack, but when Jack sees that Milton is in trouble, Jack gathers his courage and defeats Frank, causing the rest of the Black Dragons to retreat.
While Rudy, Bobby Wasabi, and Phil are away on a road trip, Rudy leaves the others in charge of the dojo, who use the opportunity to throw a party; however, it goes wrong when Kevin and his friends crash the party. Jack talks to Kevin to try to get him and his friends to leave, but he just shoves Jack out of the way. Not having it, Jack uses karate on Kevin and his friends, quickly subduing them and ending the party, but also leaving the dojo in a mess. To make matters worse, the Wasabi Warriors discover that Rudy's special katana has gone missing. Milton is able to find that a pawnshop called the Bronze Nugget Pawnshop has a katana just like Rudy's. Jack, Milton, and Kim go to the pawnshop, while Jerry and Eddie stay behind to clean up. When Jack, Milton, and Kim get to the pawnshop, they discover that the katana will cost them $500, so they try to sell a lot of their junk, only to discover that they would only get $97 for it. When Milton asks the pawnshop owner Lou to see an old French horn, he discovers something special about it and asks if Lou would give them the French horn for all of their junk, to which he agrees. Milton later reveals that the French horn belonged to Lorenzo Sanzoni, the greatest French horn maker and composer. When Lou asks Milton how much the French horn is worth, Milton tells him that they just bought his pawnshop and demands that Lou give them the sword. Later, back at the dojo, Jack, Milton, and Kim notice how clean the place is, though Jerry got stuck in a wall in the process; when everyone hears Rudy pulling up, Jack quickly puts the katana where it belongs. Unfortunately for Jack, Milton, Kim, and Eddie, Jerry later blabs to Rudy about everything while still stuck in the wall.
Jack and Jerry are practicing for a speed board competition, but it goes wrong when Jack accidentally kicks Jerry in the stomach. Jack, Milton, and Eddie take Jerry to the hospital, where he ends up getting too comfortable. When the doctor comes in and tells him that he can go home, Jerry fakes severe pain in order to stay. Kim, who is volunteering at the hospital, takes care of Jerry. Milton and Eddie get into trouble when they find a babies room and accidentally get the babies mixed up, but later discover that they have ankle bracelets for this very reason. Jack decides not to participate in the competition as he is really worried about Jerry. Jerry, on the other hand, is using his fake injury to his advantage and keeps having Kim get him pudding; however, when she returns from one of her pudding trips and sees Jerry dancing to a song, she becomes upset, and Milton and Eddie later also learn that he has been faking. Later, to get back at Jerry, Kim tells him that the test results came back as not good and that he needs immediate surgery; to keep him from escaping, Kim had Jerry strapped down to his bed. As Milton and Eddie, dressed up as doctors, attempt to start his surgery, Jerry freaks out and admits the truth just as Jack comes in. Jack becomes upset with Jerry because he was worried sick about him; in order to make things right, Jerry holds Jack's boards during the competition, which Jack ends up winning.
Jack is invited to go to the Junior World Martial Arts Championships taking place on the Great Wall of China in China, something Jack has been dreaming of ever since he got into martial arts. Jack wonders how he got invited and Rudy reveals that he wrote a letter about him and sent it to China. When Rudy talks about how amazing Jack is because he is undefeated and has never lost a match in his life, Jack asks if they can talk outside, where he reveals that he is not undefeated and that a boy named Kai beat him up so badly that he gave up karate until coming to the dojo. Rudy reassures Jack that he deserves this and reveals that he was sent two first-class tickets to China; however, Jack trades them in for cheaper tickets so that everyone can go. Later, after they arrive in China, Jack manages to win the semi-finals, but discovers that Kai is there, who he will be facing in the finals. Jack loses his confidence and reveals to Kim and Rudy that Kai is his cousin and explains that both he and Kai studied with their grandfather, but to Kai, karate was not about honor and discipline, it was about intimidation and hurting people. Kim and Rudy give Jack a pep talk and encourage him not to give up, and he agrees as he remembers the Wasabi Code. Later, Jack is ambushed by martial arts fighters in the hallway of the building the championships are taking place at; he has the upperhand at first, but is later smacked in the hand by a sneak attack, falling down in pain. Kai surprisingly shows up and rescues him. A doctor later examines Jack's hand and reveals that it is broken and Jack cannot compete in the finals. Later, Kai is given a trophy for winning the finals and Jack wants to be a good sport and congratulate him, but when he notices that the tattoo on his friend's arm is the same tattoo he saw on the arm of one of the people who ambushed him, Jack realizes that Kai set the whole thing up and had his friends ambush and attack him. After Jack tells Kai that he is afraid to fight him, Kai becomes enraged and attacks him. Kim and Rudy keep Kai's friends from interfering while Jack fights with Kai. When Jack accidentally tosses Kai over the Great Wall of China, he quickly grabs him and pulls him up; however, after Kai is back on safe ground, instead of being thankful, he resumes the fight and takes a cheap shot at Jack's hand. Despite his broken hand, which has been further injured from Kai's cheap shot, Jack manages to defeat Kai. 2b1af7f3a8