Zaruchim (ザルチム, Zaruchimu) and Raushin Mo (ラウシン・モー, Raushin Mō) are one of the major antagonists of the Faudo Arc. They're also Riou's right arm. Their spells use Shadow Magic. Zaruchim holds a grudge against Alishie due to his limitless determination that managed to intimidate him. In the anime, Zaruchim's spellbook is burned by Zatch Bell's twin brother when he comes to take over Faudo.
Zaruchim is a mamodo who has the power to see everything; although only two eyes are normally visable in his head, the scars on the crown of his head conceal his other eyes. It is these extra eyes that grant him his power. He built an alliance with Riou, in a attempt to free Faudo from his seal, and to have part of it's power. It was known that once were sent to recruit Alishie and Riya to join Faudo Cult. The two duos started fighting, but Aleshie gained the upper hand. As Alishie prepares to finish Zaruchim off with his strongest spell, Shao Neodoruk, Raushin appears with a child from Alishie's village and threatens to kill him if Alishie did not comply. Right after Faudo is free from his seal, Zaruchim was the first to ally himself with Riou and was teleported to the Brain's main room, along with Riou. From here, Zaruchim's roles alter in both the manga and the anime.
In the anime, in an attempt to stop Aleshie from defeating Gyaron, he turned himself into a false Li-en, but was easily uncovered by Kiyo after Rodeaux rold Kiyo that Wonrei was to weak and had begged Rodeaux to spare his life. Because of this, he cuts Rodeaux's spellbook into shreds and then burns it. He is later defeated by Zeno and Dufort, but is only seen when Raushin was left on the floor, with the book burned.
In the manga, Zaruchim and Fango are sent to stall time for Faudo to reach Japan and battle Ponygon and Riya. The four duos start fighting but due to the "Godufa" transformation that Fango received, his personaity changes and he becomes heartless and vicious, constantly attacking the enemy without hesitation and even going as far as to attack Zaruchim when he feels that he is in the way. Zaruchim requests that Fango fights Ponygon as he wishes to battle Alishie on his own. Fango gets overconfident as the battle continues and Ponygon and Sunbeam are able to land a heavy blow on him with their speed. Zaruchim demands if this was all Fango could do even after accepting Faudo's power and drinking Faudo liquid in the middle of the battle. This remark angers Fango and he interferes with Zaruchim's battle with Alishie, challenging Zaruchim to see who could bring down Alsihie and Riya first. Kafk and Ponygon, who sees that the two are targeting Alishie and Riya, tells them to get on Ponygon. Ponygon gains the upper hand as he and Alishie are able to work together to attack the enemy while Fango and Zaruchim were still fighting separately. After being hit by Riya's Go Amuruk, Zaruchim plays dead until Fango is defeated and uses Fango as a shield against Riya's ultimate spell, Shao Neodoruk. Zaruchim stops the group when they try to advance, anticipating that an angered Alishie would throw away his life to come at him and soughts to make him taste "true humiliation". He prepares to finish Alishie off with his strongest spell, Jiboruo Sheedon but Riya intervenes, resulting in a huge explosion and Riya's book being burnt. Zaruchim is pleased that Riya's book has been burnt and tells Alishie that even though he was unable to annihilate him with his spell, he had at least made him miserable and orders him to show his misery to him before he dies. He becomes confused when Alishie merely looks at him pityingly and states that "it's so sad", causing Zaruchim to realize that his body was turning transparent. He turns back to Raushin, who apologizes, saying that it wasn't because he was careless and sees that Kafk had already burnt his book. Before he is sent back to the mamodo world, Kafk asks him why he did not accept Faudo's power and Zaruchim replies that he had never been interested in the power of Faudo that Zeno had usurped. Zaruchim wonders if he could have won if he had battled with Riou but scolds himself for thinking that, as he wasn't even friends with Riou. He remembers how his heart had soared when he was asked to revive Faudo by Riou, feeling that he was accomplishing a monumental task and doing something amazing. But after all that hard work, Zeno came and took over Faudo, making Zaruchim feel that all of their hard work had been for nothing and causing him to wonder what he and Riou had been doing all along. It was when he saw Riou vanishing that he realized that all Riou had been obsessed with was reviving Faudo. Zaruchim then wonders why he had felt miserable when Riou had gone, reminding himself that he had never been Riou's friend, this time crying as he does so. He tells himself that this situation was no better and remarks that it was not surprising that Alishie pities him. He apologizes to Raushin for having to put up with such an idiot and bids him goodbye before fading away.
Zaruchim is later seen as one one of the mamodo that helps Zatch during his final battle with Clear Note. One month after Zatch becomes king, Zaruchim is seen in the library with Kido, Momon, Sugino, Robnos, Furigaro and Zabas.