Luka is first introduced in "Captain Hardrock". He first meets Marinette when she stumbles into his room, carrying a message from his mother to get him ready for the music festival. He startles her by accident and instantly finds this amusing, teasing her for her stuttered reaction. However, upon seeing her embarassment, apologizes for doing so and claims that he "often makes more sense with [his guitar]". She is marvelled by his musical talent and he lets her keep a one of his Jagged Stone guitar picks. Luka takes an immediate liking towards Marinette. Luka and Marinette establish an instant connection, which lasts throughout the episode; they repeatedly glance at each other during band testing.
Luka tests his guitar by strumming a note, but the speaker volume was so loud that it caused damage in the city, hence alerting the police. Officer Roger ordered them to turn down the volume, but Luka's mother refused, insisting that the band be allowed to play any way they wanted as it was the music festival. When he refused, she was akumatized into Captain Hardrock. Both Luka and Juleka were shocked by their mother's akumatization. Luka, along with the other members on the ship, refused to obey her orders, resulting in being chained and held prisoner in the ship's cabin.
With the help of Tikki, Marinette successfully broke the chain restraining her and Luka, setting them free. Once again, Luka is impressed. Upon hearing the captain's footsteps approaching the hold, the two set up a scene: Marinette hid in the drawer of a sliding bed, while Luka acted as bait to lure his akumatized mother away and was recaptured. Later on, he asked a now-transformed Ladybug about Marinette's whereabouts, to which she replied that Marinette was safe and the one that alerted her. Hearing this, Luka compliments Marinette, calling her "unbelievably brave".
After the defeat of Captain Hardrock, Adrien is granted permission to attend the music festival. He trips over a keyboard and gets excited after learning its model number, claiming that he can play it. Luka introduces himself to Adrien and the two forge a friendship.
In "Frozer", Luka accepts Marinette's offer to accompany her to the ice rink with Adrien and Kagami. Once there, he consistently looked after her and guided her on the ice. He appears to be skilled in skating, being able to keep balance while lifting Marinette with ease. The two share a happy moment together despite Marinette's watchful eye over Adrien and Kagami. At the end of the episode, after the akuma was captured and they all had to go home, Luka was not fazed when Marinette wanted to confront Adrien. In fact, he encouraged her to speak with him, despite his obvious feelings for her.
In "Mayura (Heroes' Day - Part 2)", Luka took part in the Paris Rebellion in effort to help Ladybug and Cat Noir defeat Scarlet Moth.
In "Silencer", Luka was practicing with his band and heard that Bob Roth was looking for new talent but soon discovered that it was ploy to steal Marinette's designs and have XY claimed them as his own. He and everyone left for the studio to reason with him, but when Bob Roth refused to negotiate let alone at admit the truth and worst of all threaten Marinette. Luka got so angry that he was akumatized by Hawk Moth into the titular villain, then took XY's voice away and had his eyes set on Bob. Marinette tried to reason with him and not go after his target in the name of revenge. Before Silencer left, he declared his love to her, soon he came across Ladybug and due to Bob's interference, he took her voice too.
Soon he was instructed by Hawk Moth, not to let Ladybug get away and assured him he wouldn't but wanted to have his revenge. Upon searching he admitted that Bob was good at hiding but knew how to flush him out, once he tricked Officer Roger into bringing Bob to him Silencer took his voice away as well. After backing him into a corner, Luka set everything up but was interrupted by a mute Ladybug and Cat Noir and fought against the hero until he noticed that Bob was gone.
Upon, hearing Cat Noir believe that he lost Ladybug, he used her voice to lure him out unaware he was playing into the heroes trap by activating the heroine's Lucky Charm. During a brief fight with Cat Noir he took his voice too, but seeing Ladybug suck his voice into a vacuum cleaner, Luka dropped his guard leading to his helmet being a destroyed and deakumatized coming too he was assured by Ladybug that everything was fine.
Then, heard Bob accused Ladybug of tying him and imprisoning him and as well as hear him boast about admitting what he did to Kitty Section. Leading to him smiling because Bob admitted what they needed to hear and became surprised that Bob actually does give them a chance to perform. But Luka went on stage he was asked by Marinette if he really meant what he said as Silencer, Luka answers that he doesn't remember and yet hoped he didn't say anything bad. When she replied that he didn't; Luka was relieved and unknowingly said the same love confession he admitted to her when he was akumatized before leaving to perform with his band.
In "Party Crasher", Luka was one of the many people invited to the All Boys party for Adrien at the Agreste Mansion. Until Party Crasher disrupted the event, then he and everyone else managed to escape. Seeing Cat Noir in danger he received the Snake Miraculous that, when inhabited by Sass, helped him transform into Viperion and joined him, Pegasus and Carapace to defeat the titular villain and save Ladybug. Setting his power of Second Chance he was ready to fight Party Crasher, but upon seeing Carapace captured he rewind time and tried to save him but ended up captured instead. Soon he was enjoyed by the other heroes until they were all freed by their newest ally King Monkey, following Ladybug's lead and moving with the music the team was able defeat Party Crasher. Afterwards, he returned the Snake Miraculous, helped clean the aftermath of the party and joined the girls at the Seine.
In "Reflekdoll", Luka was playing his guitar and heard his sister Juleka doubt herself about having the potential to be a model or taking Marinette's offer for modeling in her upcoming website despite that he still encouraged her to try.
In "Desperada", Luka was playing music for his friends on his family's houseboat and attempted to teach Marinette, then noticed Kagami and Adrien coming in surprised as everyone else that they were here. Upon hearing his mother, he was surprised to see Jagged Stone at their houseboat and even more so along with Juleka that Jagged and their mom had a history together. And yet, his mother refused knowing that he had a habit of firing his guitarists, and soon Vivica arrived akumatized as Desperada and soon was under fire. After saving Adrien, they both found a place to hide and was thanked for the save but noticing that Ladybug was alone he wondered where Cat Noir was but with Adrien believing that he wouldn't make in time.
Luka decided to help the heroine by distracting the villain by playing his guitar and yet was under fire again but saved by Adrien. Soon the boys followed Ladybug into the sewers where he was scalded by the hero but thanked for the save. After seeing the heroine summoned her Lucky Charm and received a gong he was curious to know what she was going to do with it. Before she left Ladybug asked if she could borrow his guitar and Luka was surprised that knew how to play as well as followed her instructions to find a place to hide.
Luka took Adrien's suggestion to hide the storage room locker while he found another place and hoped that his friend would stay safe. Afterwards, he was found by Ladybug and Cat Noir asking if they defeated Desperada and where Adrien was but heard from Cat Noir if he was hiding somewhere then he'd would find him. Having enough of waiting, Luka went off to find Adrien and ran into him with Ladybug relieved he was safe. Upon seeing Ladybug kiss him and heard being recommended for something Luka wondered if he missed something, then was offered the Snake Miraculous by Ladybug under the agreement that it must be returned after the mission. Wanting to save his friends and family he agreed to help and was greeted by his kwami Sass who helped him transform.
He met up with Cat Noir introducing himself as Viperion; when he heard the cat's playful banter about starting with a horseshoe for good luck he calmly replied that Ladybug had enough luck for both of them. Following the heroine's lead, they took away the villainess' vantage point and was tasked with preventing Desperada from playing her instruments. Agreeing he set his power in motion, while rewinding the clock to save his allies he tried to figure out a way to defeat Desperada. During his third use of Second Chance he saw that she gets distracted by music and rewinds time once more. This time he takes the lead by acting as the distraction with his lyre. By using a saddle to restrain the villainess the trio managed to defeat her and save everyone. Afterwards Luka returned the Snake Miraculous to Ladybug thanking her for trusting him. Then, he returned to home and played along with Jagged Stone and his friends.
In "Cat Blanc", in an alternate reality Luka was seen playing music on his family's houseboat as Marinette and Adrien danced together.
In "Felix", he supported Marinette and her friends decision in wanting to send Adrien a video care package, after everyone makes their videos he went below deck to play his guitar. Then, he heard Marinette rant on in fear about being rejected and makes himself known to her aware of her crush on Adrien he fully supported her if they ended up together. As well as be here for her if she and Adrien didn't work out hearing Marinette say that Adrien replied they decided to listen to his message but became shocked that "Adrien", said those terrible things. He agreed with Marinette that their friend wouldn't say those things, afterwards Luka along with Juleka and Rose received a thank you video from the real Adrien.
In "Heart Hunter (The Battle of the Miraculous - Part 1)", Luka was working on his song for Marinette and bike rode to her house to let her hear a sample but hearing her say that she had to hurry to the Le Grand Paris hotel Luka gave her a ride. However, sometime later, he came across Marinette again asking if she was okay and sadly saw that she wasn't. Hearing her voice out her frustrations about not being her true self around one and Luka says that she can always be herself around him, as well as telling him anything or nothing as he embraced her.
In "Miracle Queen (The Battle of the Miraculous - Part 2)", afterwards Luka was still aware that Marinette still had feelings for Adrien but their moment was ruined with a swarm of hornets coming for them and he protected Marinette. Then was instructed by the titular villain to come to her by following Miracle Queen's command to transform taking the Snake Miraculous turning into Viperion and used his powers against the heroes. Until Dragon Bug and Cat Noir managed to retrieve his Miraculous and after Miracle Queen was defeated he and the others were set free. Spending time at the Seine Luka was asked by Marinette to play his song for her which he does on his guitar.