Ray and his friends are introduced to the world of the Kaijudo Duel Masters, a secret order of heroes sworn to protect mankind from fantastical creatures—and from the evil forces of The Choten, who would use those creatures to conquer the world.
Ray, Allie, and Gabe explore the wonders of the Kaijudo Temple and learn the basics of creature dueling. The Kaijudo Duel Masters are impressed by Ray's abilities (but skeptical of his unconventional techniques) when he summons the powerful creature, Tatsurion the Unchained.
Ray, Allie, and Gabe bond with some creatures and contend with a deadly threat inside the Kaijudo Temple! The kids must join the Kaijudo Duel Masters and their creatures in a battle to save the day.
The kids must track a small creature and banish it back to its realm. But when The Choten mutates the creature and it starts to duplicate itself, things get complicated. Meanwhile, Gabe has problems controlling his new primary creature, GARGLE.
After rescuing a baby fire creature from Alakshmi, Ray and his friends hide out at school, but are soon caught up in a dangerous game of hide-and-seek with The Choten's protégé and her vicious creature, Razorkinder.
A mysterious stranger helps Ray, Tatsurion, and Gabe find Allie and a creature named Squeaky when they are captured by the soldiers of Lord Skycrusher. Tatsurion reveals he is of 2 civilizations like Ray: Fire and Nature.
The stranger turns out to be a bounty hunter named Saguru and delivers the kids to Lord Skycrusher. Tatsurion invokes his right to trial by combat and Ray and Allie are his opponents. Ray helps Tatsurion to use his Nature side to resist the mind control of Skycrusher's sword. Everyone manages to escape, while Saguru steals the FireSword and delivers it to the Choten for a slight look at Earth.
A series of strange robberies has been hitting the city. Ray, Allie, and Gabe discover that a thug named Heller is behind the robberies and has been using a gauntlet that he stole from Choten's men to control a Storm Patrol creature called Shaw K'Naw. During battle, Ray is temporary blinded and Master Jaha ends up having to train him to use his other senses to see while training with a Tarborg creature called Fumes.
Ray and his pals help Master Kimora probe some mysterious disappearances occurring in Mighty Shouter's tribe. Upon being caught by a claw emerging from the portal, Ray and Tatsurion discover that Choten and Aqua Seneschal are behind the abductions. Now Ray must find a way to free Tatsurion and the other captives of Choten without being spotted by Choten's minions.
The kids try to stop Alakshmi, Fingers, and Heller from obtaining the mana which Master Chavez needs to replenish the Veil to keep the Fire Civilization King from awakening.
Upon infiltrating Ray's house, Choten and Aqua Seneschal use a bunch of Memory Swarm to steal all of Ray's memories of Kaijudo. It's up to Allie & Gabe to get them back by traveling into the Water Civilization for the backup. Yet they soon get caught upon being accused of stealing a Water Civilization artifact and are brought before the Council of Logos.
Narrowly escaping the Water Civilization rulers after being accused of stealing their most powerful artifact, the kids team up with Gabe's creature Gargle to prove that the Choten is guilty—and to stop him from getting away with his crime.
While on a mission to hunt down a primitive Bigfoot-like creature known as the Roaming Bloodmane, Ray and the Duel Masters quickly discover there is far more to the beast than meets the eye.
Allie has a sleepover to ease the tension among her friends, but Alakshmi crashes the sleepover with Gorgeon, Shadow of Gluttony.
Ray and Tatsurion duel in an arena competition for the Shield of Unity (an artifact that compels all other tribes to help whichever tribe possesses it) in order to help Gabe, Master Chavez, and Earthstomp Giant protect the Quillspike Tribe from the attacks by Midnight Crawler. While watching the battle, Allie notices that the Choten is in the audience and discovers he has created a plot to steal the Shield of Unity with Saguru posing as a Snow Faerie.
Ray and Tatsurion the Unchained must race Saguru and those in the finals to get to the Shield of Unity. When the Shield of Unity is stolen by Aqua Seneschal, Ray and Tatsurion the Unchained end up working with Saguru to recover the Shield of Unity. Meanwhile, Gabe, Master Chavez, and Gargle try to find a way to get out of Midnight Crawler and find a way to prevent it from eating more of the Quillspike Tribe's land.
Gabe follows his brothers to an abandoned amusement park at the old pier while tutoring them. Meanwhile, Fingers uses Impalicus (which Choten evolved from a Writhing Bone Ghoul) to target Gabe in order to find Ray. Now Gabe is put to the ultimate test to keep his brothers from getting attacked by Writhing Bone Ghoul before they see it.
Ray and Allie end up in a high stakes battle of wits against Alakshmi, Heller, and Saguru when the Choten makes another attempt at stealing the Helm of Ultimate Technology which has been hidden in the bank where Allie's father Arthur Underhill works. Gabe also alerts the other Masters in order to save the hostages and help to fight off the Choten's minions.
Following the incident at the bank, Master Jaha, Master Chavez, and Master Nadia leads an expedition to the Darkness Civilization to rescue Allie's father and endures multiple attacks. They soon learn from Master Jaha's contact Slyth that Arthur Underhill is in the clutches of Megaria, the Collector.
With Allie a prisoner of Megaria, Ray and the others formulate a plan to rescue Allie and return home with the Shield of Unity. Meanwhile, Alakshmi enters the Darkness Civilization in order to redeem herself to Choten and claim the Shield of Unity only for Megaria to have Razorkinder Puppet of Miasma Pit knock out Alakshmi. Now Megaria has Allie and Alakshmi fight each other to see who will become her pawn in a plot to expand her territory.
While trying to teach Carny a lesson following an incident at a parent-teacher conference, Ray and Tatsurion the Unchained find themselves stuck in the Fire Civilization with Carny and they must work together find their way back to Earth while evading Lord Skycusher's bounty hunters Blastforge Slavetrader and Burnclaw the Relentless. During this time, Ray ends up making a discovery about Carny's dad Alex where it turns out that Alex is one of Choten's benefactors and even learns more about Tatsurion the Unchained's father: Napalmian the Conquering.
Sasha, Channeler of Light returns to Earth upon being sent by the Light Civilization to study humans. While in a mortal disguise, Sasha is introduced to mean attitudes, cyber-bullies, and powerful emotions. All of this makes her question the humanity of humankind. At the same time, Alakshmi trains Carny to duel like her.
Master Nigel has sent the other Duel Masters and Acolytes to look for Choten's spell. Sasha, Channeler of Light sends a message to Gabe that the Light Civilization is under attack. The kids and Master Nigel travel to the Light Civilization to find Alakshmi (wielding the Sword of Fiery Cataclysm), Fingers (wielding the Cloak of Dark Illusion), and Heller (wielding the Shield of Unity) attempting to steal the final powerful artifact called the Heart of Light where the artifacts that Choten's minions wield act as a compass to the Heart of Light.
The Choten, Alakshmi, Fingers, Saguru, and Heller attack Ray’s apartment to get the fifth and final Creature Artifact. Making matters worse, The Choten activates a Summoning Inhibitor that prevents anyone or anything from crossing through the Veil within the targeted perimeter. During this time, Ray learns about his mother's past and what his father Ken was.
Now that the Choten has all five artifacts, he begins his plan to collapse the Veil and awaken the 5 Creature Kings. Ray, Gabe, and Allie escape from the Creature Realm and help the Duel Masters launch an attack on Choten's lair unaware that the Choten is prepared for their arrival by abducting Tatsurion the Unchained and the creature partners of the Duel Masters. Tatsurion the Unchained evolves into Evo Fury Tatsurion and grows wings. The Choten successfully awakens King Tritonus (the monarch of the Water Civilization).
As The Choten's plan appears to be falling into place upon awakening King Tritonus, Infernus the Immolater, Almighty Colossus, Queen Kaleema of the Infinite Dark, and Eternal Haven Angelic Liege, Ray, Gabe, Allie, and the Duel Masters must do everything in their power to save Earth from being changed forever.
In the second-season opener, a war breaks out between the Fire and Water Civilizations, resulting in some strange natural disasters.
Ray and Bob are abducted and taken to a Volcano warship, so a rescue attempt gets underway while the warship is at risk of being attacked.
Alakshmi must be saved from the Volcano-ship; a Water Creature is investigated by Allie and Gabe.
The kids advance to a new training level and get access to the dojo, which temporarily allows them to acquire strange new powers through an old spell.
A classmate threatens to expose Kaijudo by posting photos of Carny and a Fire Civilization creature on the Internet.
Cyber Lord Finbarr needs help explaining the king's bizarre actions and the Choten's culpability in things.
The kids look for a mystic who might lead them to a cure for Ray's dad.
Ray travels with his grandfather to Japan, where he learns details of his family history and meets a creature that grows enormously as it absorbs mana.
Plant life grows unruly, so the gang head to the Nature Civilization, where they try to defeat the Wild Veggie creatures.
Ray gets a good job and moves into a new home with his family. Elsewhere, the Choten's henchmen start a new crime spree.
Gargle visits Gabe's house and encounters Gabe's brothers. Elsewhere, Ray heads to the chemical plant after something odd occurs there.
Empress Megaria wants Allie to be her apprentice. Elsewhere, a truck carrying evolution serum vanishes.
Allie's loyalties to her friends are tested; Ray learns about non-violent resistance, and he uses his new knowledge when confronting Empress Megaria about Allie.
The kids are in peril at sea as they search for the San Campion Triangle; after August questions Saguru's compassion, the two of them engage in a duel.
Humans get replaced by look-alike holographs, so Ray seeks help from his uncle; Allie performs a spell and accidentally casts the temple into darkness.
Bob's mom gets abducted and taken to the Fire Realm, so Ray and Bob go on a rescue mission. However, the mission gets more complicated when Bob encounters adversaries from his past.
Ray receives a warning in a dream, so he and his pals cross the Veil and enter the Nature World. While there, Ray looks for a mystic who may possess the healing spell he seeks.
The kids and Master Isao unexpectedly find the Choten's ship, but making an undetected escape isn't feasible for them. Meanwhile, Alakshmi gets creative as she attempts to remove Sensei's armor.
Allie gets stuck to Alakshmi, so they join forces to combat Nigel as he tries to devise a Veil breach. Elsewhere, Ray and the Masters learn that the Choten is reaching out to the Darkness Realm Queen.
At the time when Carny is back in school, a bullied kid named Kevin steals one of Carny's tech-gauntlets and inadvertently opens the Veil which lets the Skeeter Swarmers into the school that take over everyone's bodies except Ray's body. Now he is the only one left to fight against this. Meanwhile, Queen Kalima starts to have her forces invade San Campion where the incidents with the Skeeter Swarmers gives Gregoria the opportunity to invade San Campion.
Ray has a family reunion with Master Isao. Meanwhile, Butterfly Effects prove harmful to San Campion.
The Water Realm causes damage to two other realms, so the kids seek help from four creatures who can join forces and ward off another attack.
Ray barters with the Choten, giving him a spell from the Water Mystic in exchange for a remedy for his father.
The Creature Monarchs must be gathered together in one locale in order to free Tritonus and halt the impending war in the Creature Realm.
The Adepts board the Choten's ship and figure out the plan for the missing evolution serum. Meanwhile, things fall into place for the Choten.
Ray gets to use coveted spell to halt the Choten's army, but it comes at a high personal cost.
