Legendary Heroes[]
Naofumi Iwatani[]
Itsuki looked down on Naofumi because he considered him to have the weakest weapon. Because he was easily gullible, he believed Malty's accusation that Naofumi attempted to rape her and berated Naofumi without hearing or believing his side of the story. Despite that, Itsuki stood up for Naofumi after the rigged duel when he pointed out Malty's involvement in it. He also demanded to know the reason for revoking Naofumi's payment as he didn't get any job from the guild to support himself. He readily believed Naofumi was guilty of stealing his achievements even without evidence to back up that belief and still tried to insist it was true even when it was proven otherwise. He believes Naofumi to be an evil person and readily accepted any accusations made against him without question, such as Naofumi brainwashing the people and kidnapping the second princess.
After Naofumi's name was cleared, he agreed to the queen's idea of giving a little preferential treatment to Naofumi, in-order to balance all the past misdeeds against Naofumi, but Naofumi felt he was just saying that for show and was sure that he would throw a tantrum. Itsuki doesn't like the idea that Naofumi is more powerful than he is in general but more specifically because he feels that Naofumi's job (The Shield Hero) should be weaker than his own and felt him to be bossing him and other heroes. He openly accused Naofumi of cheating to try and outshine him. This directly led to his involvement in the spirit tortoise incident.
After becoming possessed by the Pride curse, Itsuki became more hostile towards Naofumi thanks to the lies Witch told him, believing Naofumi to be evil. Although Naofumi did agree that Itsuki accusations about him working his slaves hard while keeping all the profits to himself as true, everyone on Naofumi's side (including all of his slaves) denied this and point out that he was like a parent for them.
Likewise, Naofumi didn't view Itsuki in good light for he sees Itsuki as a self-centered, approval-seeking person. However, what little respect he had for Itsuki completely disappeared when Itsuki kicked Rishia out of his party for being weak.
Ren Amaki[]
Itsuki along with Ren and Motoyasu fought the wave bosses. Ren was also able to reason with Itsuki about how there was little to no evidence of pinning Naofumi of stealing Itsuki's accomplishment. Though he firmly believes Naofumi to be a villain, Itsuki was willing to listen to Ren's suggestion of investigating the back story of the kidnapping incident, to see if Naofumi was really telling the truth.
In times of Itsuki being affected by the curse series, Naofumi bought Ren to reason with him, considering their past closeness. They were shown to be seated next to each other during the times of rigged duels. All this shows a certain degree of trust between them.
Despite fighting alongside him, Itsuki was just as surprised as Naofumi after leaning Ren's way of working with his comrades.
Motoyasu Kitamura[]
Itsuki was a little envious of Motoyasu's preferential treatment. Itsuki along with Ren and Motoyasu fought the waves and the final bosses. Itsuki along with Ren called out Motoyasu on his rigged duel with Naofumi. Motoyasu considered Ituski and Ren as his buddies and went on a rampage against Naofumi after being falsely informed of Naofumi's involvement in their deaths. Later, he joins with Naofumi to fight against the Pope for the same reason and vows to avenge them and give them a proper funeral, but is surprised when they turn out to be alive.
Vassal Weapon Holders[]
Raphtalia[]
Itsuki was originally under the same impression as Motoyasu, that Raphtalia was being forced to work under Naofumi, which reinforced his bad opinion of Naofumi because he was from a time and place where slavery wasn't tolerated and thus branded as evil. However, after Naofumi's name is cleared, he asks Raphtalia about her relationship with Naofumi and her thought of wanting not to fight and be free, but her negative reply betrays Itsuki's feelings and thoughts, which were seen in his face.
Glass[]
Glass defeats Itsuki with great ease, believing him to be a normal adventurer and wonders aloud where the other heroes are. While she acknowledges Naofumi alone to be a hero.
Aultcray Melromarc XXXII[]
Aultcray gives much respect and somewhat reasonable treatment to Itsuki. Itsuki questions his mistreatment of Naofumi with rigged battle and cancellation of funds, leaving Aultcray speechless. When Aultcray's crimes were exposed by the queen, he along with Ren calls the punishment of the king befitting.
Companions[]
Rishia Ivyred[]
Itsuki rescued Rishia from an evil Nobleman. From then on Rishia follows Itsuki obeying his orders to the letter, though she was mostly mistreated by her fellow peers. Rishia mostly reminded Itsuki of himself from his original world and tried to bury it. Itsuki and his comrades forced her to focus on her weak points rather than sharpening her strong skills. Itsuki finally snapped when Rishia received praise from the queen for being useful in handling L'Arc while he wasn't. Because of that he framed her and kicked her out. When questioned as to why by Naofumi, he replied that she was too weak and did it for her own good, which pushed her to try and commit suicide. Later, Risha grows strong under Naofumi to prove Itsuki that she isn't weak and that she can be someone worthy to stand by his side.
Despite knowing Itsuki's flaws in his personality and methods, Rishia still holds Itsuki in high regard and her love for him doesn't deter. Even when she becomes a member of Naofumi's party, her feelings for Itsuki remain strong and still tries to defend him from any insults.
When Itsuki becomes influenced by his weapon's curse, Rishia finally makes her stand towards Itsuki, determine to save him. Itsuki continued to look down on Rishia as simply an obstacle to reach Naofumi. However, Rishia manages to prove him wrong by finally defeating him when his own bow grants Rishia the power of a Vassal Weapon.
After Itsuki lets go of his curse and suffer its consequence where he becomes apathetic. Left in debt by Malty, he begs Rishia for forgiveness and chooses to stay in Naofumi's village as he recovers.
Mald (former)[]
Mald was one of his original companions selected by the Melromarc government upon him being summoned. Originally Itsuki had a very "positive" relationship with Mald due to his attention seeking tendencies and arrogance getting the better of him and Mald's own sycophantic tendencies to feed Itsuki's ego only made him all the more easier to be manipulated by Mald.
It was evident that due to Itsuki's childish and trusting personality and desire to be praised eventually lead him to trust and believe whatever Mald told him by just complementing and feeding his ego. Causing Itsuki to believe whatever he told him.
Mald himself was shown to have never actually cared about Itsuki and only cared about the benefits being the companion to one of the Legendary Heroes would bring him as a Nobleman. He later showed little to no shame on turning on him after the Spirit Tortoise Disaster started by Itsuki (and the other heroes sans Naofumi,) and literally used him as a scapegoat to avoid punishment. Later he had little to no shame in taking advantage of Itsuki's vulnerable mindset after awakening his Curse Series to manipulate him to go against Melromarc, fight in the arena's, and take all of Itsuki's earnings for his own hedonism.
Welst (former)[]
Welst was assumed to have respect for Itsuki as he immediately chose to accompany the bow hero from the start. Welst like Itsuki had a lot of pride and did not like being showed up by anyone else, this was especially evident when he conspired with the other members of the bow heroes party to frame and banish Rishia after she had assisted Naofumi during the wave at Cal Mira which gained her notoriety over all of them. However in reality, Welst did not care for Itsuki at all as he only cared about himself which was shown when he along with the other members of the Bow Heroes Party abandoned Itsuki during the battle with the spirit tortoise.
Welst would reunite with Itsuki later on along with the other members of his party and Bitch (Malty), they worked together to trick Itsuki into fighting in underground battles and win money from them. Welst and the others used the money for themselves while lying to Itsuki that the money was for the poor. After learning that Naofumi had arrived to find Itsuki, Welst along with his party members and Bitch abandoned Itsuki leaving him with their debt. This in combination with learning that he had been lied to and used broke Itsuki completely.
Rojeel (former)[]
To Itsuki, Rojeel was a trusted companion who helped him become a hero and enact "justice". However, when Rojeel was given the opportunity to join Malty, he decide to betray Itsuki for an easier life.
Spear Girl (former)[]
The spear girl was assumed to have respect for Itsuki as she joined his party right at the beginning of the series. She is seen whenever Itsuki was around and helped during his battles such as the waves. Spear girl was shown again, along with the Bow hero’s party during the wave at Cal Mira, where she along with the other members of the bow hero’s party minus Rishia were beaten by L’Arc and Therese. After Rishia had taken the spotlight during the third wave, spear girl and the other party members worked together to frame Rishia and have her expelled from their party. However, Spear girl revealed that she did not care for Itsuki at all, this was shown during the Spirit Tortoise Incident, where she along with the other members of the Bow hero’s party abandoned him, which allowed Kyo to capture him.
Later on, she along with her party members and Bitch (Malty) reunited with Itsuki and tricked him into fighting in underground battles to win them money that they spent for themselves. They lied to Itsuki and tricked him into believing that they were using his winnings to help some slaves, when in reality they were using the money for their own purposes. However, when she and the others learned that Naofumi had arrived for Itsuki, they abandoned him and left Itsuki with their debt. This in combination with Itsuki learning that he had been tricked and manipulated broke him completely.