He is a wealthy, generous boy who specializes in Aquos. He is the Brain of the Brawlers, a real walking encyclopedia. He loves to play Bakugan and to work on strategies. He used to be extremely obedient to his parents out of fear, but that changed when he joined the Brawlers; however he is still very obedient. He now has no regrets for the past, realizing that he only wanted to make his parents happy. Marucho has a butler named Kato, though Kato is not usually around Marucho anymore, due to the fact that Kato is now working for Marucho's father.
In the Japanese version, Marucho speaks in a polite and formal keigo accent, thus putting honorifics in his speech and uses honorific suffixes when addressing a character's name, such as Dan-san and Drago-san.
His Guardian Bakugan is Aquos Preyas, who crashed Marucho's house party, which was thrown after he moved into Dan's town. Preyas was sent to the Doom Dimension in Marucho's battle with Klaus von Hertzon which made Marucho want Preyas back so much that when Klaus opened up his portal, Marucho followed him.
Later, when Klaus shows up with Preyas Dan and Runo find a way to get Preyas back by using the ability Pure Light. Preyas evolved into a two-sided Bakugan called Angelo and Diablo by coughing them up. Unlike the other Bakugan however, Preyas multiplies when he evolves, so Marucho got to keep the old Preyas. He multiplied into Angelo/Diablo Preyas. Preyas also has a move called "Change of Attribute" with which he can take advantage of the opponent’s Gate Card. When Marucho was being tested by Frosch he had to fight an old version of himself, the one who always listened to his parents. This sickened him but he was able to accept his past and how it made him who he is today and passes the test. When he brawled against Dan with Preyas and Angelo/Diablo Preyas he was ranked seventh. Preyas Angelo/Diablo are not in New Vestroia.
When he was in Vestroia he fought Aquos-Ventus hybrids Taygen and Hairadee alongside Shun. He originally just fought Taygen but then they teamed up when they realized that they were both able to use both Aquos and Ventus. He then defeated them by using a Diagonal Relationship with Ventus and Haos with Angelo and Skyress, and then a Pyrus and Darkus with Preyas and Diablo, defeating them. He later brawled against the Taygen once again alongside the JJ Dolls Jenny and Jewels and defeated it.
Marucho later goes to the Resistance headquarters and gains new clothes. By Marucho's Mission, he's disappointed with himself, as he is part of the Resistance, yet doesn't have an Aquos Bakugan. Marucho decides to leave for a bit so that he can look for one.
While walking through a jungle, he is caught in a trap set up by a Bakugan called Elfin. Elfin gives him some food while she explains about how she knew Preyas before he got captured. Marucho then decides that they should team up, but Elfin wants Marucho to prove himself that he's really the "right partner" for her.
Suddenly, Mylene Pharaoh comes in and tries to steal what's left of the Aquos Bakugan (Wontu), so Elfin and Marucho team up to fight her. With Elfin's rather interesting abilities and attribute change, Marucho was winning until Mylene pulls out her trap Bakugan. Marucho manages to pull himself together for one last attack before he passes out. Shun Kazami saves him from losing and losing Elfin. Elfin reveals that she received training from Preyas and has decided to become his Guardian Bakugan.
In Surprise Visitor and Gate Crashers, Marucho and Elfin challenge Shadow Prove, who was blocking the portal under Prince Hydron's commands. He manages to defeat Shadow, much to Shadow's embarrassment and Mylene's annoyance.
However, Marucho is defeated by Volt Luster when the team is split apart, and disappears, like Ace. He is then freed by Mira and Spectra Phantom and manages to escape Beta City with the others. While in Gamma City, Marucho battles alongside Shun against Mylene and Shadow and wins. Marucho's purpose for battling at Gamma City is so Dan and Ace could go to destroy the third Dimension Controller.
In Spectra Rises, he helps Dan and Mira to defeat Spectra, but they just narrowly beat the new Helios MK2 with their combined powers. After the Resistance comes back to Earth, Marucho allows everyone to stay in his mansion and puts up a shield so the Vexos won't be able to track them as long as the stay in the house. In Elfin On the Run, he comes back to fight Shadow Prove and Hydron with Preyas and Elfin, and although he wins, Elfin still loses the Aquos Energy.
After Keith joins the Resistance at the end of Spectra's Last Stand, he and Marucho start working on Battle Gear for Drago in Fusion Confusion and Volt's Revolt, called JetKor. After some testing in Bakugan Interspace with the prototype, they manage to succeed in creating it.
In the Japanese special ending, he is shown explaining Alice Gehabich and Shun how the Interspace works.
He is the most intelligent of the brawlers and has a new outfit in Gundalian Invaders. His new Guardian Bakugan is Akwimos. After Ren gave him a new Phantom Data, Marucho created Bakugan Interspace which allowed all brawlers around the world to battle each other.
He was revealed to have finally released Bakugan Interspace to the entire world, and was ranked #3 on the Interspace rankings. He gave Jake his first Bakugan, which is a digital copy of Subterra Coredem, the Subterra Bakugan that arrived in Bakugan Interspace when it received the "Unknown Data."
In a tag brawl with Dan against Sid Arkale and Lena Isis, Marucho did not last long, as Akwimos ended up showing a weakness to Phosphos's venom. Marucho was able to help Drago by nullifying Sid's Gate Card, allowing Dan to win the brawl.
After Fabia's battle against Jesse, Ren runs away without admitting that the Gundalians are the ones that attacked the Neathians, and Marucho is the only one that believes that Ren is innocent. He then battled Ren and revealed his new battle gear, Gigarth. He won and realized that Ren was lying the whole time.
Marucho and Jake battled Sid and Casey using the real Akwimos and Coredem. In the end, they win, and Marucho captures Casey's Buz Hornix. Marucho makes an avatar of himself to brawl alongside Fabia against Lena and Zenet. Then he sneaks in to try and shut down Bakugan Interspace. Ren finds him and tells him of his past. He also plants a computer virus to allow the Brawlers to hack inside.
In Decoy Unit, he and Jake faced off against Airzel and Mason Brown in order to buy enough time for Dan, Shun and Fabia to bring the Second Shield back online. Marucho also proves his worth as a brilliant military strategist by coming up with a decoy strategy to distract the Gundalians while they try to reactivate the second shield; as Queen Serena states later; he is a gift to Neathia.
In The Secret of the Orb, he and Fabia battle against Ren and Nurzak. During the battle, Marucho reveals that he still has not gotten over Ren's betrayal and gets very emotional and angry. Later, the Sacred Orb sends a dimensional twister as a warning, thus ending the battle. Later, back the palace, Marucho said that the Orb acted the way it did was because it was because two friends were fighting on the battlefield. Marucho then says that even though the others will think he is crazy, he believes Ren will come back to the Brawlers.
Marucho faces off against Stoica when Emperor Barodius launches another attack, and ends up losing. However, he regains his friendship with Ren. Shun and Marucho help Dan get inside the Gundalian castle to rescue Jake. Soon after, he and Shun get separated from Dan. The two of them end up fighting Gill and Airzel. Although they managed to defeat Airzel, they still lost to Gill and fled.
He battled against Jake after disguising himself as a Gundalian Guard, but the battle ended up being a tie when the force of Akwimos' and Coredem's attacks knocked him out of the Gundalian fortress. He was caught by Shun and Hawktor.
He chooses to stay behind and battle Airzel and Strikeflier, but eventually retreats and meets up with the rest of his team for a battle against Airzel, Gill, Stoica, and Kazarina. They win and retreat to Neathia, leaving Fabia behind to battle Kazarina.
On Neathia, he battles Zenet until Kazarina's death snaps her and Contestir out of hypnosis. She joins the Castle Knights in the battle against Barodius and Phantom Dharak.
He attempted to battle Phantom Dharak, but was defeated in a single hit. He is woken up by Linehalt's forbidden power, and later says goodbye to Akwimos, the Neathians, and the Gundalians before being teleported back to Earth.
In Interspace Showdown, it is revealed that Marucho has a new Guardian Bakugan, Aquos Trister which is from Gundalia. Also, he turned over administrative duties of Bakugan Interspace to the system, allowing it to expand but also attracting sleazy characters such as a card dealer named Dylan. He later observes Dan's battle against Ben but then sends out Trister to stabilize the arena when Drago loses control of his powers.
In Mechtogan Mayhem, he is seen battling Jack Punt, a member of Team Anubias. At first he and Trister were struggling but were starting to come back before Zenthon appeared. They tried battling him but Trister was defeated by Zenthon's laser blast. The battle was declared a draw due to Zenthon's interference. He comments later "that Mechtogan has the same destructive power as Drago".
In Disconnect, he and Shun try to offer encouragement to Dan to tell them what is going with him and that they will always be there for him. Dan just makes another excuse and walks away. Later when he and Shun are watching Dan's battle with Anubias - they realize that Dan is holding Drago's power back and that is what he has been hiding but they do not know why.
In Fall From Grace, he and Shun went to talk to Dan at his house but was not there. Later they appear to be spying on Dan and Drago's training session. Later he and Trister helped out Dan battle Zenthon along with Shun and Taylean but are unsuccessful at defeating him.
In Tri-Twister Take Down, he and Shun battled the Tri-Twisters and their Cyclone Percivals before Sellon and Anubias interfered with the battle due to be three to two with Krowll and Horridian. In episode 7, he battled the Bash Brothers and their Bakunano and he was losing before Shun appeared and beat them.
In A Royale Pain, he tries to stop Shun from entering the Battle Royale, which fails. He then teams up with Paige and Rafe to stop Silent Strike, who wreaks havoc in Interspace. After he disappears, Shun and Marucho have a talk with Paige and Rafe who reveal themselves as Gundalian and Neathian, and tell them what Mechtogan really are. He then leaves after Rafe calls the Brawlers weak, and he has a meeting with his dad on quitting the Brawlers.
In Back In Sync, his father asks him to quit the Brawlers and help fix Interspace from a different viewpoint. But after a talk from Trister, Marucho decides not to quit. Then, he battles Jack Punt and wins the battle without losing any life points, making his father and Kato proud.
In Mind Search, he participates in the Capture the Flag challenge along with Shun, Rafe and Paige. During the challenge, Marucho tries to teach Rafe and Paige to not battle people to reduce violence. As Marucho's plan succeeds and they win the flag, he regains Rafe and Paige's trust and they become friends.
In Re-connection, he battles against Sellon and Shun. He wins against Sellon but loses to Shun. Throughout the battle, Marucho tries to convince Shun to stop battling as much. In the end, this worked and Shun and Marucho are reunited.
In Triple Threat, he congratulates Rafe for winning his battle. He also begins his battle against Anubias and Robin alongside Shun but the battle is interrupted by the chaos in Bakugan Interspace.
In Interspace Under Siege, he tries to stop the ensuing chaos in Bakugan Interspace. He sends a SOS to all the brawler allies and Spectra was the first one to receive it. He also received BakuNano Crosstriker from Rafe.
In A Hero Returns, he stops Dan from using Drago and sends back the brawlers into the interior of BI. Paige and Rafe told Dan that while he was away, Marucho was the leader of the Brawlers (much to his surprise). He seems to be worried about Dan's attitude. After that, he goes with the Brawlers to save Gundalia from Mag Mel and the Chaos Bakugan.
In Gundalia Under Fire, he popped out of the interdimensional portal right at the Gundalian front lines. He then meets up with Ren. He later makes an ambush strategy. This fails because Mag Mel uses his ability to see through Dan. He uses Crossstriker only to be beat minutes later when Mag Mel and Razeniod arrive. He then hears about the 'gate and key' that Dan and Drago apparently posses.
In Battle Lines, he tells Dan to stay behind in while the rest of them continue to defend Gundalia. But Dan does not listen to him and goes on his own way, much to his anger. Later, when Dan battles Anubias and Sellon, he finishes off a pair of Mechtogan using Cannonfury and he and Dan start fighting until he receives a message from Ren, telling him that Rafe and Paige are gone. Marucho finds them to sneak into Mag Mel's castle. The group begins to argue but a Flash Ingram blasts them and they fall into the chasm below.
In Unlocking the Gate, he is angry after Rafe tells him that Dan went on his own way again, but after he convinces Marucho that Dan accepts his ideas and truly cares for him and the Brawlers, he starts crying. Later, he fights some Chaos bakugan and six Mechtogans alongside the brawlers. When the brawlers were having trouble with the Mechtogan's, Dan and Drago share their powers with the others and they summon their Mechtogan for each of the Brawlers and Marucho receives Aquos Accelerak for Trister. After that, they win the battle and Gundalia is saved. He and the other brawlers later accept Dan back as the leader of the brawlers.
In True Colours, he and the Brawlers returned to the Bakugan Interspace, to find in ruins. They were later attacked by the Chaos Bakugan, Anubias and Sellon. The Brawlers then found out Anubias and Sellon that they are artificial life force created by Mag Mel and that they work for Mag Mel. In the end, they were able to win. After the fight, they find out that the access point has been damage and are trapped inside Bakugan Interspace forever.
In Dangerous Beauty, he tried to figure out a way to repair an access point in Bakugan Interspace. He later watched Shun taking out an Iron Dragonoid while discussing what to do with Sellon. He also coached Rafe and Paige in defeating other Iron Dragonoids that were invaded Interspace.
In Behind the Mask, he was struggling to find a way to get a message to the outside world. He was then approached by Dylan who would form a key and help Marucho get out a message to Kato and his Dad.
In Dark Moon, he and Trister worked together to get a message to Dan and Drago about the gate and key. Razenoid knocked out Trister and harmed Marucho along with the other Brawlers. Marucho's plan worked as Dan and Drago broke free and lured Mag Mel and Razenoid to the Dark Moon.
In The Final Takedown, he continued his attempt to defeat the Razen Titans.
In Evil Arrival, he battled Gunz, but lost. He later battled Mechtavius Destroyer and was beaten,however Dan managed to defeat the Mechtavius Destroyer with his Dragonoid Destroyer.
In Mysterious Bond, he discussed the matter of Wiseman and his Bakugan with Mira and the others, and he was shocked to learn that Dan was battling Wiseman and Nonets.
In Combination Impossible, He tries to cheer up Radizen after he finds out that Drago and Jaakor were able to do a combination while he still couldn't. Marucho would go to his father's power plant and tell Radizen that it didn't matter if he could fuse or not since he is still a strong Aquos battler. They are soon confronted by Wiseman, Radizen easily beats Wiseman's Bakugan but they fuse together giving Radizen a tough time. Roxtor then fuses with Radizen and the two defeated the fused Bakugan. Marucho and Mira would then have a conversation how some things never change.
In Enemy Allies, he would battle alongside the other brawlers and have Radizen fuse with Roxtor to battle against Wiseman's Mechtogan, but their combination was ineffective as both Shun and Marucho were defeated while trying to defend Dan who was already knocked out. He would hear Runo's voice as she sent Radizen a new Battle Suit. Together the brawlers would defeat Wiseman.
Bakugan Battle Brawlers
- Aquos Preyas (Guardian Bakugan)
- Aquos Angelo/Diablo Preyas (Second Guardian)
- Aquos Siege
- Aquos Stinglash
- Aquos Limulus
- Aquos Juggernoid
- Aquos Terrorclaw
- Aquos Robotallion
- Aquos Fear Ripper (video game only)
- Aquos Griffon (video game only)
- Aquos Falconeer (video game only)
- Aquos Gargonoid (video game only)
Bakugan Battle Brawlers: New Vestroia
- Aquos Preyas (First Guardian- Reunited with in episode 26)
- Aquos Elfin (Third Guardian- Received in episode 4)
- Aquos Minx Elfin (Third Guardian- Evolved in episode 27)
- Aquos Akwimos (Fourth Guardian- Digital Clone obtained in episode 52)
- Aquos Tripod Epsilon (Bakugan Trap)
- Aquos Wontu
Bakugan: Gundalian Invaders
- Aquos Akwimos (Fourth Guardian- Digital Clone- then the real Akwimos in episode 8, left on Neathia)
- Gold Gigarth (Battle Gear left on Neathia)
- Subterra Coredem (Given to Jake- Digital Clone)
- Ventus Buz Hornix (Taken from Casey)
- Haos Aranaut (Digital Clone - Offered to Jake in episode 1, but Jake chose Coredem) (used by Avatar Marucho in Escape From Darkness)
Bakugan: Mechtanium Surge
- Aquos Infinity Trister (Fifth Guardian Bakugan) (Obtained prior to Interspace Showdown) (Went to New Vestroia prior to Evil Arrival)
- Silver Crosstriker (BakuNano) (Infinity Trister's BakuNano) (Received from Rafe)
- Aquos Cannonfury (Received from Rafe)
- Aquos Accelerak (Mechtogan - Made from Dan and Drago's power) (Infinity Trister's Mechtogan)
- Aquos Radizen (Sixth Guardian Bakugan) (Obtained prior to Evil Arrival)
- Subterra Roxtor (Seventh Guardian Bakugan) (Borrowed from Mira)
- Aquos Blasterate (First Battle Suit) (Given by Mira)
- Aquos Clawbruk (Second Battle Suit) (Given by Mira)
- Aquos/Subterra Betakor (BakuFusion Combination)
- Aquos Flytris (Created from the 20% energy reserve of the Dragonoid Destroyer) (Radizen's Mechtogan)
- Ventus/Aquos Duomechtra (Mechtogan Combination) (Shared with Shun)
Former Bakugan Dimensions Bakugan
- Marucho has had the most Guardians with two or one under his ownership, as Shun only had Ingram after Storm Skyress decided to stay in New Vestroia, Drago being Dan's only Guardian, and most of the other characters being absent from the events of other seasons.
- Marucho is the youngest out of the 6 by 1–3 years.
- Marucho has a strong relationship with Ren, as he helped make Bakugan Interspace happen, before he learns that Ren lied to the Brawlers the whole time. As seen in Mechtanium Surge, they are still close friends.
- The name Marucho comes from Marukura Choji.
- He is one of the seven characters that have appeared in all four seasons; the other six are Dan Kuso, Drago, Shun Kazami, Julie Makimoto, Miyoko Kuso, and Kato.
- His personality is similar to Rekuta from Duel Masters; he possesses a high level of intelligence, and he also tends to worry when an opponent pulls out a surprise ability that may nullify that of his own Bakugan, or surpass the power of the latter.
- His personality is also similar to Kenny from Beyblade, and Kenny's Beyblade is called "Hopper", which is also Akwimos's Japanese name.
- After season 1, Marucho's forehead birthmark became much less prominent.
- Marucho is the only member of the Brawlers whose Guardians are from all worlds seen (Preyas, Elfin and Radizen from Vestroia/New Vestroia, Akwimos from Neathia, and Trister from Gundalia).
- In the Japanese version of the anime, Marucho's Bakugan all speak with a Kansai accent.
- Marucho shares some similarities with Yai Ayano from MegaMan Battle Network. Both are the smallest, youngest, and richest of the team; they are also both blond.
Bakugan Battle Brawlers
|Bakugan: Battle Brawlers|
|JJ Dolls (Tag with Dan Kuso)||7-8||Win|
|Takashi and Kosuke (Tag with Runo Misaki)||9||Win|
|Shun Kazami (Tag with Runo Misaki)||11||Lose|
|Klaus von Hertzon||17||Lose|
|Klaus von Hertzon, Chan Lee and Julio Santana (Tag with Dan Kuso and Runo Misaki)||21-22||Win|
|Masquerade (Tag with Shun, Runo and Julie)||28||Lose|
|Hairadee and Taygen (Tag with Dan Kuso, Shun Kazami, Runo Misaki and Julie Makimoto)||41||Win|
|Taygen (Tag with the JJ Dolls)||46||Win|
|Centorrior and Druman (Tag with Dan Kuso, Runo Misaki, Julie Makimoto, Klaus von Hertzon, Julio Santana, Billy Gilbert, and Komba O'Charlie)||50-51||Win|
|Hal-G (Tag with the Battle Brawlers)||51-52||Win|
Bakugan Battle Brawlers: New Vestroia
|Bakugan: New Vestroia|
|Unknown Brawler||8||Lose (on purpose)|
|Mylene Pharaoh and Shadow Prove (Tag with Shun Kazami)||22-23||Win|
|Spectra Phantom (Tag with Dan Kuso and Mira Clay)||31||Win|
|Hydron and Shadow Prove||35||Win|
|Shadow Prove and Lync (Tag with Ace Grit)||40||Lose|
|Zenoheld (Tag with The Resistance)||51-52||Win|
Bakugan: Gundalian Invaders
|Bakugan: Gundalian Invaders|
|Sid Arcale and Lena Isis (Tag with Dan Kuso)||2||Win|
|Sid Arcale and Casey (Tag with Jake Vallory)||8||Win|
|Airzel and Mason Brown (Tag with Jake Vallory)||15||No Outcome|
|Nurzak and Ren (Tag with Fabia Sheen)||19||No Outcome|
|Gill and Airzel (Tag with Shun Kazami)||30||Lose|
|Gill, Airzel, Kazarina and Stoica (Tag with the Battle Brawlers)||36||Win|
|Zenet Surrow||37||No Outcome|
|Barodius (Tag with the Battle Brawlers)||38||Lose|
Bakugan: Mechtanium Surge
|Bakugan: Mechtanium Surge|
|Jack Punt||2||No Outcome (Zenthon appeared and beat both of them)|
|Zenthon (Tag with Dan Kuso and Shun Kazami)||4||No Outcome|
|Tri-Twisters (Tag with Shun Kazami)||5||No Outcome (interrupted by Anubias and Sellon)|
|Bash Brothers (Tag with Shun Kazami)||7||Win|
|Capture the Flag (Tag with Shun, Paige, and Rafe)||12||Win|
|Anubias and Robin (Tag with Shun Kazami)||14||No Outcome|
|Chaos Bakugan (Tag with Shun, Paige, Rafe, and Spectra)||15||Win|
|Anubias and Sellon (Tag with Dan, Shun, Paige, Rafe, and Spectra)||15-16||No Outcome|
|Mag Mel (Tag with Dan, Shun, Paige, Rafe, and Ren)||17||Lose|
|Anubias and Sellon (Tag with Dan and Shun)||18||Win|
|Mag Mel, Anubias and Sellon (Tag with Dan, Shun, Paige, Rafe, and Spectra)||19||Win|
|Anubias and Sellon (Tag with Dan, Shun, Paige, and Rafe)||20||Win|
|Chaos Bakugan (Tag with Dan, Shun, Paige, Rafe, Spectra, Ben, Jack, Robin, Noah, Chris, and Soon)||24||Win|
|Razen Titan Army (Tag with Shun, Paige, Rafe, Spectra, Gus, Ben, Jack, Robin, Noah, Chris, and Soon)||25-26||Win|
|Coredegon, Slycerak, Exostriker and Mandibor (Tag with Dan and Shun)||27||Win|
|Wiseman (Tag with Dan and Shun)||28||Win|
|Wiseman (Tag with Mira Clay)||31||Win|
|Wiseman (Tag with Dan and Shun)||32||Win|
|Wiseman (Tag with Dan and Shun)||35||No Outcome|
|Wiseman (Tag with Dan and Shun)||36||Lose|
|Wiseman (Tag with Dan and Shun)||37||Win|
|Slycerak, Exostriker, and Mandibor (Tag with Dan and Shun)||39||Lose|
|Wiseman (Tag with Dan and Shun)||40||Lose|
|Coredegon, Slycerak, Exostriker and Mandibor (Tag with Dan and Shun)||41||Lose|
|Mechtavius Destroyer (Tag with Dan, Shun, and Gunz)||45-46||Win|