Mamoru is a short, thin man with red-brown hair in a bowl cut, brown eyes with the bottom eyelashes styled into triangles, stylized eyebrows, and dimpled cheeks. He wears a navy blue coat with a yellow lining over a red waistcoat and a high-collared black shirt done up with twin columns of brass buttons, in addition to white pants and grey shoes with black soles. The forearms of his coat appear to be padded and are patterned with yellow lines. Mamoru also has thick grey pads of cloth over each shoulder with yellow diamonds on the front that have yellow lines extending from their upper tips. He carries an old-fashioned pocket watch that he wears around his neck on a grey string and stores on one of the brass diamonds that his shoulder pads are set with.
Mamoru is an extreme control freak, fretting over tardiness and reacting in overblown horror to the sight of Gloria and Grace Tyler Dueling the Lancers. Like most Duel Academy members, he shows no concern at the thought of sealing people into cards; indeed, Mamoru worries that it is not being done fast enough. He is also somewhat narcissistic; he frets that he will be punished by the Professor if the Arc Project falls behind schedule and worries about the absence of Aster Phoenix because it is putting him under stress. He dislikes the nickname of "Noroma-chan" (blockhead) given to him by Grace.
It is seen that unlike most Duel Academy agents who believe in the agenda, his motivations are mostly self-centered. He wishes to carry the missions given to him (completing the Arc Project and eliminating the Lancers) in order to get the full-credit for the accomplishment. In fact, he even wished for his superior to lose to Yuya so Aster wouldn't get any praise for it. Deep down however he has shown to be highly inept as he must relay orders to others to accomplish his goals, while denying the fault of any failure from his part, further showcasing his uselessness. A final blow to this would be the fact he is not a duelist, as confirmed by Noro himself upon being challenged by Kite Tenjo.
Aster left the Heartland base one day, causing Mamoru to angrily stress over his absence, the Arc Project falling behind schedule and the possibility that the Professor would scold him. He ordered everybody to seal everyone in the Xyz Dimension into cards as soon as possible and he wondered where the Commander-in-Chief was. He later learned that Duelists who used Pendulum Summoning, had appeared in Heartland and informed the Professor without telling Aster. The Professor sent the Tyler sisters to the Xyz Dimension, but they did not arrive on time, stressing Mamoru again as he wondered where they were. A student informed Mamoru that the Tyler sisters were Dueling the Lancers and showed him a visual of it. Mamoru stopped the student from informing Aster of the news and he told the student to keep it a secret from the Commander-in-Chief, as he had not told Aster that he requested reinforcements from the Professor to deal with the Lancers. Mamoru explained that he would personally go out to the Tyler sisters. Mamoru found Gloria and Grace just after they had been defeated, and he tried to get them to go after the Lancers again, but Obelisk Force had arrived to eliminate them. As the Obelisk Force challenged the Lancers to a Duel, Mamoru explained to Gloria and Grace that the Professor sent them in case they lost. While Mamoru watched the Duel, he complained when Yuya Sakaki and Shay Obsidian didn't lose according to his calculations. The notorious Resistance Duelist Kite Tenjo arrived and saved Yuya from the attack of "Chaos Ancient Gear Giant", and Mamoru surmised that he joined forces with the Lancers. He was surprised when Kite defeated the Obelisk Force and Aster arrived with a squad to defeat Yuya.
Mamoru tried convince Aster that he didn't have to personally deal with the Lancers, only for Aster to silence him and warn Mamoru that he would be dealt with later. While Aster Dueled Yuya, Mamoru sent the rest of Aster's squad to deal with the Lancers. However Kite defeated them and Mamoru was shocked that one Duelist could defeat an elite squad. Gloria criticized Mamoru for losing the squad and he began to worry about losing his position if Aster defeated Yuya. Mamoru was shocked when Yuya Fusion Summoned "Brave-Eyes Pendulum Dragon", but pleased when Yuya was close to defeating Aster. Gloria caught him siding with the enemy, though Mamoru tried to den it. He was displeased when Aster turned the Duel in his favor. As Aster launched a final attack, Mamoru thought the Duel was over, and Gloria asked him whether or not he was disappointed. Yuya survived, but Aster continued to dominate the Duel, and Mamoru continued to worry about losing his position as Deputy Commander. Mamoru panicked even more when Yuya fell to 100 LP, and he tried to think of a plan. He was pleased when Yuya was about to perform, but had to hide his pleasure when Gloria caught him again and he decided to call for more reinforcements just in case. He was surprised by Yuya's plan and pleased when Aster couldn't beat it. When Aster tried to attack with "Destiny HERO - Dystopiaguy", Mamoru mentioned that it didn't have enough ATK but he was surprised when Aster increased the ATK of the monster. He watched as Yuya defeated Aster and was pleased that his position was safe. Gloria was worried about the Professor learning of Aster's loss, but Mamoru reassured her that he had called in reinforcements, who surrounded Yuya and Aster.
Mamoru announced that he would exterminate the Lancers after Aster and the Tyler sisters had failed. Just as he ordered them to attack, Aster defended Yuya and he declared his treachery against the Professor to everyone's shock. The Tyler sisters joined Aster as well, and Mamoru declared himself the Commander-in-Chief and ordered his soldiers to attack. However, Kite returned with the Resistance and reminded Mamoru that he should be facing him first since he was on Duel Academy's wanted list. Kite challenged Mamoru to a Duel to see if he had the resolve to put his life on the line, but Mamoru surrendered out of fear after Aster's speech. Now officially allied with both the Resistance and Lancers, Mamoru and other former members of Duel Academy helped the refugees in the Resistance's hideout by distributing foods, medical supplies, and rebuilding residential houses for free to atone for what they had done.
Following the battle against Zarc, Mamoru appeared during Yuya and Dennis McField's Duel with Gloria, Grace, and Aster. He watched the remainder of the Duel and was pleased when Yuya won. Mamoru was later seen watching Yuya's Duel against Jack Atlas with Gloria, Grace, Aster, Kite, Allen, and Sayaka. He also watched Yuya and Declan's Action Duel. Mamoru was happy that Yuya won both Duels and was sent to the Pendulum Dimension by Ray Akaba to witness her revival as Zuzu Boyle.
- ↑ 1.0 1.1 Yu-Gi-Oh! ARC-V episode 106: "An Academic Test"
- ↑ 2.0 2.1 Yu-Gi-Oh! ARC-V episode 109: "Surprise Showing"
- ↑ 3.0 3.1 Yu-Gi-Oh! ARC-V episode 108: "Twins with Tudes"
- ↑ 4.0 4.1 4.2 Yu-Gi-Oh! ARC-V episode 104: "Fighting Between The Rubble"
- ↑ Yu-Gi-Oh! ARC-V episode 107: "Belles & Whistles"
- ↑ Yu-Gi-Oh! ARC-V episode 110: "Fenced In"
- ↑ Yu-Gi-Oh! ARC-V episode 111: "Last Laugh"
- ↑ Yu-Gi-Oh! ARC-V episode 112: "Hat-Trick"
- ↑ Yu-Gi-Oh! ARC-V episode 144: "Showtime Showdown"
- ↑ Yu-Gi-Oh! ARC-V episode 146: "One Way Street to Defeat"
- ↑ Yu-Gi-Oh! ARC-V episode 147: "One Last Duel"
- ↑ Yu-Gi-Oh! ARC-V episode 148: "That's a Wrap!"