When the Nighloks are revived and begin to attack the mortal realm, Jayden of the Shiba Clan takes arms to fight them as the Red Samurai Ranger. After defeating a company of Moogers, Jayden is informed by his mentor, Ji, that he must assemble his team of Samurai Rangers instead of fighting on his own. Meanwhile, on the Sanzu River, Xandred finally awakens, and upon learning that the Samurai Rangers still exist, becomes enraged and sends the Nighlok Tooya to attack the humans with an army of Moogers. Ji summons four other warriors: Olympic swimmer Kevin, kindergarten teacher Mia, carefree gamer Mike, and pure-hearted country-girl Emily. Upon meeting the four, Jayden gives each one a chance to back out of his crusade, and when all four decline, he gives each one a Samuraizer phone. Jayden, Kevin, Mia, Mike and Emily then take on Tooya and his numerous Moogers. Red Samurai Ranger defeats Tooya, but in spite of that, he tells his teammates to remain on their guard. Sure enough, the Nighlok is reborn as a mega monster, so the Samurai Rangers enlarge their Foldingzords to confront and destroy him. After the battle, Ji welcomes Kevin, Mia, Mike and Emily into the Shiba House and all five warriors become full-fledged Power Rangers.
After joining Jayden as his teammates, Kevin, Mia, Mike and Emily begin their transition into Samurai Rangers. However, while Mike spars with Kevin, Emily disappears. Kevin, Mia and Mike discover her practicing at a nearby park, where she reveals her reasons for becoming a Samurai Ranger. Meanwhile, Bulk is reunited with Spike, the son of his best friend Skull, and he becomes committed into training his nephew into becoming a samurai. When the Nighlok Scorpionic appears, four of the Samurai Rangers deal with the Moogers while Red Samurai Ranger fights the new Nighlok. In the midst of the battle, Red Samurai Ranger keeps a young girl out of harm's way before the Samurai Rangers defeat Scorpionic with their combined Spin Sword attacks. But when Scorpionic revives into a Mega Monster, the Samurai Rangers combine their Foldingzords to form Samurai Megazord to destroy him and his giant Mooger army. After the battle, Ji congratulates the Samurai Rangers while Mike uses his symbol ability to create confetti before dancing all over the house.
The Samurai Rangers are seen training, but Mike can't seem to sense Jayden or Kevin's attacks. Mike soon leaves practice to hang out with his friends, telling them of his struggles. However, the city is attacked by the Nighlok Rofer, sent by Xandred to raise the Sanzu River's water levels with human fear. Even in his Ranger form, Mike is no match for Rofer as the others arrive as the monster falls back to rehydrate. Jayden explains to Mike that being a Samurai Ranger is the ultimate sacrifice and must stay away from his friends and family to protect them. After giving it thought, Mike gets an idea and starts to train himself as Jayden undergoes his own training. The next day, when Rofer resumes his attack, Mike once again takes on the Nighlok on his own, tricking him into tangling up his arms. Mike then executes the finishing move. When Nighlok is revived and enlarged, despite Mike's intent to finish him off himself, the Rangers form their Megazord and use Jayden's training to finish the monster off.
After confronting the Nighlok Doubletone, the Rangers search for the young boy whom the monster was talking to, a little leaguer named Ryan. Kevin and Mia find the boy, only for the boy to refused to answer them as he runs off. Following him to his home to learn whatever secret he has, the two get into a discussion of Kevin's personal regret of his life-long dream that he has been keeping to himself before Mia assures him he'll live his dream once Xandred is defeated. After an all-night stake out, Kevin and Mia find Ryan on the move as he suddenly disposes of his baseball stuff and calls Doubletone as he performs his end of the promise, hurting himself so he cannot play baseball in order to get his father back. However, as the garbage truck arrives to take out the trash, Doubletone revealed it to be a lie as part of his plan to make the boy cry to overflow the Sanzu River. Vowing to make the Nighlok pay, Kevin and Mia fight him as the others arrive, defeating Doubletone as he revives into a giant before Samurai Megazord destroys him. Later, the Rangers attend Ryan's game after the boy learns the garbage man saved his stuff and gave it to his coach, with Jayden using his Symbol Power to ease Ryan.
While the other spend their leisure time at the Rainbow's End amusement park, Jayden remains behind to master the use of the Beetle Disk as the rest of the team encounter the Nighlok Dreadhead. whose flexible body and marksmanship overpower them. Even with the Red Ranger's arrival, the team are no match for Dreadhead before he falls back when he begins to dry up. After revealing the Beetle Disc to the others, Jayden resumes training into the night, nearly destroying himself in the process. The next day, a rehydrated Dreadhead resumes his attack with the other Rangers arriving to fight him as Jayden arrives and succeeds to using the Beetle Disc to have his Fire Smasher assume Cannon Blast Mode in order to destroy Dreadhead. When Dreadhead resurrects into a giant, he overwhelms Samurai Megazord until Jayden uses the Beetle Disc to summon the Beetle Zord. To counter the summoned giant Moogers, the Beetle Blaster Megazord is formed to take them out before destroying Dreadhead. After the fight, Jayden joins the others at the amusement park.
During battle training, Emily accidentally injures Mike in the arm, Emily's attempts to care for his arm making a mess of everything. The Nighlok Negatron appears and subjects his victims to insults that hurt their feelings so deeply that the verbal abuse actually becomes a physical assault. Confronting him all the Rangers are struck down by Negatron's attacks save for Emily who is unaffected as the Nighlok is forced to retreat. When her teammates wonder about her immunity to Negatron's attacks, Emily tells them how her sister Serena taught her to ignore insults and how you need to keep thinking that the person never even said it. When Negatron resumes his attack, Emily succeeds in weakening him with Mike's help as Jayden destroys him with the five disc Beetle Cannon. Negatron revives as a Mega Monster and the Rangers destroy him with the Beetle Blaster Megazord. Later, the Rangers are then seen walking along the sidewalk while Mike carries Emily who lose consciousness at the end of the fight. Mia hears an ice cream truck and Emily, who has been faking unconsciousness for a few minutes at least, pretends to wake up so they can all get ice cream.
While having breakfast, the Rangers learn that the Swordfish Zord has been sighted off the coast as the poisonous Nighlok Yamiror appears. While the others go after Yamiror, poisoned as a result, Kevin is sent to acquire the Zord by fishing for it. But after failed attempts to catch it, Kevin receives the aid of a fisherman before being contacted by Ji and being told that the others got poisoned and the Swordfish Zord is needed to cure them. As Jayden slows Yamiror down in spite of the pain from the poison, Kevin finally manages to fish the Zord out with the fisherman's help. After curing his teammates of Yamiror's poison before they change to use the Fire Smasher's 5-Disc Swordfish Cannon mode to defeat the Nighlok, Kevin summons the Swordfish Zord to battle the enlarged mega monster before having it combine with the Samurai Megazord to form the Swordfish Fencer Megazord to destroy Yamiror. As the Rangers spent a day at the beach, a mysterious figure who witnessed the Rangers' fight with Yamiror walks off into the night.
Dayu and the Moogers start kidnapping brides, so the Samurai Rangers use a fake wedding to try to trap her. After she doesn't show, they make Jayden and Mia pose as another couple at a wedding, which leads to Mia being kidnapped. However, Dayu noticed the trap and also kidnaps the real bride, whom turns out to be Emily in a disguise. After almost sending the Rangers into an ambush, the Rangers challenge Dayu to a battle in the nearby forest and quarry. After trying to destroy her however, a new Nighlok named Deker shows up, and Jayden catches his attention. After a sinister comment, Deker and Dayu return to the Netherworld.
Nighlok Madimot, shows Master Xandred that he found and possessed the Red Rangers Tiger Zord and claims it as his pet. Madimot attacks in the forest and the samurai Rangers rush towards the Nighlok. Madimot fires a blast at Mike but Kevin gets in the way and takes the blast. Kevin becomes possessed and Madimot orders him to attack the others. Kevin fights Jayden and Jayden rushes towards Madimot but he is forced to get Mike, Emily, and Mia out of there. Madimot and Kevin attack a construction site and the Rangers arrive. Deker returns to his human form and watches the fight between Kevin and Jayden with the other Rangers commenting on Jayden's abilities. during the fight, Jayden frees Kevin from Madimot's control and the 5 then attack Madimot and destroy the Nighlok. Madimot returns enlarged and summons the Tiger Zord, the Rangers get into their zords and Jayden's lion zord battles the tiger zord and frees it. With the Megazord fused with the Tiger Zord. They finish Madimot once and for all.
Jayden and Ji tell the others that the Tiger Zord, the Swordfish Zord, and the Beetle Zord can combine into the Samurai Battlewing, a bird-like Megazord and they try to find a fitting pilot for each support zord. Jayden keeps the Tiger Disc, Kevin keeps the Swordfish Disc, and the Beetle Disc is given to Mia, much to the dismay of Mike. Mike starts to train harder than usual, but he thinks he can't catch up to Jayden and Kevin's progress. Then, when the Rangers face a new Nighlok named Desperaino who uses the loss of hope, Kevin attaches his Swordfish Disc onto the Hydro Bow to try to stop it. When Mia tries to attach the Beetle Disc onto her Sky Fan, the Nighlok knocks it away, and the disc is caught by Mike. Mike attaches the Beetle Disc onto his Forest Spear, but when Kevin and Mike try to launch attacks onto the Nighlok, the Forest Spear doesn't work and the Nighlok gets away. After the battle, Ji scolds Mike for acting so foolish and jeopardizing the team's mission. Subsequently, after locating Mike at an arcade, Ji leads him to a clearing and tries to teach him about harnessing the Forest Symbol. Then, after another encounter with the Nighlok, Mike destroys it. After a final offensive on the enlarged monster by employment of the Samurai Battlewing auxiliary Zord combination, the Rangers celebrate victory. Mia allows Mike to keep the Beetle disc. Mike creates a plant for Ji to symbolize their growing friendship.
Master Xandred is troubled by how much Deker knows about his past and about the Seal that brought him to his defeat centuries ago. Furious, he called upon giant and standard Moogers to attack the city destroying everything. Bulk and Spike encounter the Moogers and tried to put up a fight but end up running for life instead. Spike is rescued by the Pink Ranger and begins to develop a crush on her. The 2 female Rangers battle the standard Moogers while the male trio take on the giant Moogers in the Samurai Battlewing. Later, a new Nighlok named Robtish appears in a form of a swordsman and challenges Jayden to a duel. The other Rangers follow on and are defeated by the Nighlok's power. When the Nighlok takes aim at the Red Ranger, Deker appears, announcing that Red Ranger is his opponent. The trio then fight in a triple threat match when the Nighlok end up losing and retreating back to the Sanzu river. Deker and Jayden continue to fight but Jayden is defeated and takes a minor blow. Mike calls for Ji to bring help so that Emily and Kevin can be brought back to the Shiba house. Back at the Shiba house, Jayden secretly leaves his comrades and goes on a journey alone in order to protect them.
Jayden leaves the Shiba House to keep the other Rangers out of danger. Meanwhile, Emily and Kevin start to feel better, and they worry about Jayden. Kevin tells the group that he had an idea of combining the Samurai Battlewing with the Megazord. Back in the Sanzu River junk, Octoroo says Master Xandred won't be happy when he finds out Jayden is still alive. Robtish replies he couldn't finish Jayden off because of a half-human and Dayu (who is also half-human) thinks it is Deker. Xandred awakens, angered by the fact Deker is helping the Rangers and sends his Moogers to fight Deker. This leads him into getting into a fight with Deker himself. Jayden wanders around the city at night and the next day, he finds a boy crying because he misses his father, who is currently at work. Jayden says he misses his father, who is presumed dead. Jayden creates a paper airplane for the boy like his father did with him, and soon, the other children playing around make airplanes as well. Jayden says in his mind it should always be monster-free, until Robtish and some more Moogers arrive. He fights them, and is soon helped out by the other Rangers. Jayden now believes he needs his team to succeed and when Robtish grows bigger, they destroy him with Kevin's new idea for the Battlewing Megazord.
Returning after what seemed to be a false detection of a Nighlok attack on the Gap Sensor, the Rangers find an arrow with a note on it that says See You Soon. With Jayden sensing something from before within the house, it starts to haunt him. Deciding to investigate the Gap Sensor, the team encounter a fish-seller whose hand writing matches the note. After the seller gives them the slip, Kevin and Mia go to find Jayden while Mike and Emily track down the fish seller. Kevin and Mia find Jayden confronting the Nighlok named Vulpes who is spying on Jayden to find out the Shiba sealing character. With his mirror medium destroyed, the Nighlok overwhelms the 3 with his magic as Mike and Emily arrive with the fish seller following. But even all 5 Rangers are no match for the Nighlok as they revert to normal. The fish seller arrives to their aid, transforming into the Gold Samurai Ranger. After taking out the Moogers in blinding speed, the Gold Ranger battles the Nighlok and destroys him. When the Nighlok revives, he overpowers the Battlewing Megazord until the Gold Ranger enters the fight in the Octozord to weaken the Nighlok so the Battlewing Megazord can land the deathblow. After the fight, Jayden reveals he already knows the fish seller as his childhood friend Antonio.
As Antonio heads to the samurai mansion, the others listen to Jayden and Mentor talk of young Antonio-- How Jayden gave him the Octozord, how Jayden threatened to quit his training if Ji tried to take back the Octozord, etc.-- Antonio makes an entrance, fancy, then gets embarrassed when his fish hook rips his pants. Antonio explains that after moving away when he was a kid, he trained himself to be a samurai and built his Samurai-Morpher from a trashed cellphone to communicate with Octozord through text-- because the Zords understand the Rangers who were born into the Samurai heritage. Ji, feeling that Antonio lacks discipline and true samurai training confiscates Antonio's morpher, which he later doesn't react too well to. Jayden agrees with Mentor despite Antonio begging Jayden with memories of childhood friendship. As the Rangers fight the Nighlok Steeleto (who vows to avenge Vulpes), they're powerless to destroy it. Steeleto retreats when he starts to dry up and the team start to consider bringing Antonio along. Antonio, down at the fishing pier, angrily talks with Octozord about regretting meeting the Rangers. Mike and Emily go to ask him to join and go to the mansion. There, Jayden is convinced to give Antonio back his morpher just in time for the next attack by Steeleto. When the Rangers arrive, Antonio struggling to get in to a heroic position, they begin fighting and Steeleto is overpowered when Jayden and Antonio tag-team it. Once Steeleto mega-sizes, Antonio combines the Octozord with the Samurai Megazord and defeats Steeleto. To celebrate, Antonio cooks fish barbecue and everyone appreciates Antonio's membership.
Ji and Antonio announce that Antonio is fixing the Claw Zord that was damaged in battle long ago and Ji hid it. Kevin doesn't fully accept Antonio as a true Samurai and thinks he's just goofing around. The monster of the day steals kids' toys to make them cry and Octoroo trying to find another way to open the Sanzu River through a well. Bulk and Spike are sleeping and their toy panda is stolen and all that is left is slime. Dayu visits Deker outside the Sanzu River but around it, he's still injured. Dayu wonders if Deker really does remember anything from his past. Antonio follows Kevin's morning routine to learn what makes him a true samurai. The two end up in the forest finding Octoroo but their morpher signals are blocked. Antonio and Kevin eventually overcome their differences and fight together to defeat the Nighloks.
While the Rangers, minus Emily are decorating for Emily's birthday, Splitface a Nighlok, who steals spirits, attacks the city. Splitface, easily takes down Mike, Antonio, Mia, Jayden, Kevin, and Emily. The Nighlok then takes Emily's spirit, putting her in a sleep. Splitface mocks the Rangers, telling them they only have twenty-four hours to defeat him, or Emily and the other people, who he stole spirits from will be asleep forever. Splitface then tells them he is leaving and never returning. While back in the Shiba house, Emily wakes up and tells the other Rangers she is sorry for letting him get her and she feels empty before falling asleep once more. Mike goes crazy and goes back where they fought Splitface, calling him a coward and demanding he comes out to fight. Deker suddenly appears and tells the Rangers the only way to get to the Netherworld is to betray their human life and become Nighloks. Just as they are going to give themselves up, Antonio appears saying he knows how to save Emily and everyone else. The Rangers use their symbol power to activate the Claw Zord, and summon the Nighlok. Splitface can't use his special power, Body Swarm, for Antonio marked him. Antonio uses the Claw Zord, with the help of the Battle Wing to defeat Splitface and return the spirits. Later the Rangers celebrate Emily's birthday, as well as the Claw Zord's.
Jayden takes The Rangers to the Tengen Gate where they meet the gate's guardian, Daisuke, to hand them the Black Box- a weapon made by the first Red Samurai Ranger centuries ago, but was never finished. Daisuke tells the Rangers a folk tale about a Nighlok king who turned a woman and the man she loved into Nighloks. While Xandred is locked up, a Nighlok named Arachnitor tries to overthrow him and tries to force the sealing symbol from Jayden. Octoroo, because of Arachnitor, poisons Jayden as the Rangers sit for tea, trying to get the special sealing symbol from him. While Jayden is poisoned, the other Rangers face off against Arachnitor, but are doing poorly without their leader. While the Rangers are distracted, Deker kidnaps Jayden when Antonio confronts Octoroo, planning on purging the poison in him in a nearby river so that they can finally duel. Before Arachnitor can finish the Rangers off, Xandred drags him back to the Sanzu River for trying to overthrow him. After all the Nighloks disappear, Antonio is left wondering what to do, with Jayden missing and his friends unconscious.
Deker uses the nearby river to purge the poison from Jayden so that he can recover enough to duel Deker. While Antonio tries to work on the Black Box, the others Rangers recover, leave their ranger discs for Antonio to access the Black Box, and end up fighting a mutated Arachnitor. When Antonio cannot finish the Black Box, because he does not have enough strength to use any more symbol power, he instead locates Jayden and saves him right before Deker can duel Jayden. Though both weakened, Jayden and Antonio then join the others and they all manage to repel Arachnitor before the giant Moogers attack the city.
Furious with Dayu for not following his orders to destroy Deker, Master Xandred sets fire to her beloved harmonium when she was provoking him to destroy her. Devastated, Dayu escapes into the human world to fix it. Meanwhile the Samurai Rangers end up facing the Nighlok Rhinosnorus who traps Dayu, as well as the Gold and Pink Rangers in a dream world. Jayden uses his symbol power to open a portal to the Dream World allowing Mike and Kevin to enter, but severely exhausts himself in the process, preventing himself from tagging along. In the dream world, aside from Bulk and Spike's ridiculous fantasies of being samurai, Mia learns that Deker and Dayu were both once human and are the two humans previously mentioned in Daisuke's story. After Rhinosnorus is defeated, Deker shows up to challenge an exhausted Jayden.
Continuing from the end of the last episode, Deker demands Jayden to duel him. Jayden tells Deker he only fights to protect the innocent and not out of amusement. Deker gives him 24 hours before they duel or else he will start attacking innocent people, should Jayden fail to show up. Kevin and the other rangers try to talk Jayden out of fighting Deker alone and instead defeating him as a team. Jayden refuses and tells them he must be the one to duel Deker or Deker will never give up. Just as Jayden prepares to leave the next day, Rhinosnorus attacks once more and Jayden puts Kevin in charge of leading the team while he fights Deker. The Rangers defeat Rhinosnorus while Jayden battles Deker. The battle rages on, with both combatants evenly matched. Eventually Jayden allows Deker to injure him to get close enough to finish Deker off. Deker's sword Uramasa is broken and half of it gets struck into the ground nearby. Deker thanks Jayden for the Ultimate duel, which has released him from his Nighlok curse, before vanishing in a puff of smoke. Back at the Shiba house, Jayden thanks Kevin for leading the team in his absence as they all celebrate their victory.
In the Nighlok afterlife, the defeated Nighlok Monsters hold a Halloween party and recap their battles with the Rangers to each other which Master Xandred views from his mirror. All the Nighloks told their versions of how they were taken down by the Samurai Rangers. After the stories, the Nighloks vow never to bring up the Samurai Rangers at their next Halloween party. At the end of the episode, Master Xandred is displeased at not being invited to the afterlife party stating I would have been the life of the party. Octoroo states to Master Xandred that the party was meant for those in the obituary.
While reflecting on their first year together, the Rangers learn the meaning of Christmas. Emily reflects on the year through a letter to her sister Serena by writing about their adventures and fun times. Meanwhile, Bulk tries to make his first Christmas with Spike memorable and recap about their moments of comical relief, also their near encounters with the Rangers. The next morning on Christmas Day, everyone opens their presents except Mike. Feeling left out, Mentor tells him to go to the front door where Mike finds a green Motocross bike. As he returns home, he tells the others that he gave the bike to these two guys who have nothing and is grateful for what he has, the others, and wanted to give them something special. It turns out that Bulk and Spike are the guys Mike gave the bike to and they are last seen riding it chasing Santa in the night sky wishing everyone happy holidays.
Professor Cog, a minion of Venjix's forces, comes to the Samurai Ranger's dimension to take samples of the Sanzu River in a plot to poison humanity in the RPM dimension. As the Samurai Rangers enjoy an afternoon, Grinders- robotic minions in PR:RPM- attack a construction crew on a bridge. When the Rangers' swords were ineffective in harming the Grinders, RPM Ranger Red, Scott Truman, arrives and destroys all the Grinders. At the Shiba house, Scott tells the others that he can't de-morph for fear that their atmosphere may kill him because he is more accustomed to the polluted atmosphere of his dimension. Xandred and Cog attack Gold Ranger Antonio to lure out the others. When the Rangers respond, Cog opens a portal to his world and sends all but the Red Rangers through. To finish the two red Rangers, Cog shoots them with special ammo that will cause them to slowly distrust and kill each other. Later, a large gathering of Moogers and Grinders are detected, and Jayden races Scott to the location. Scott confronts Jayden about cheating in the race and eliminate a bunch of minions as they finish each other off. It turns out that Mentor-Ji saw through the betrayal ammo and used a symbol to remove the effects. As Jayden and Scott tag-team the army of Nighlok, the others return thanks to the RPM rangers sending them back. Both Red Rangers trade use of the Shark Power Disc to overpower and destroy the Mooger army. At the end of the episode, Scott says farewell, and wishes Mike luck with Emily telling him he sees the way Emily looks at him. He tells him to wait for the right time to tell her.