Kurome: Kurome is the member of the Jaegers that Wave has the closest relationship with. The two get along well and are often seen together. Over time they develop a strong and caring bond. She even tells him about her fear of being disposed of by the Empire after she's weakened by injuries, which she sustained in a battle with Night Raid. He has silently declared that he'll protect her, and has done so several times. An example being taking a hit for her that would've killed her otherwise. He is also very protective of Kurome and attacks Syura when the latter attempted to take Kurome as his new toy. Over the course of the series, Wave develops romantic feelings for Kurome, which she returns. He cares for her greatly, most notably about her health. When Kurome went to fight Akame, Wave didn't allow her to leave and was even going to stop her with force if necessary. Kurome kissed him to distract him and knocked him unconscious afterwards. The kiss made Wave realize his feelings for her, and later declared his love for her after stopping the fight between the two sisters. He even destroyed Kurome's Teigu and defected from the Empire with her. After the revolution, he stayed with Kurome and helped her recuperate her health and personality.
Esdeath: He respected his leader greatly but was also terrified of her and her harsh punishment for failure. Esdeath has noted that she regarded Wave as both incredibly strong and very talented, and that he had almost perfected his strength. Wave appears to have great faith in Esdeath, and was relieved to have her back when she returned to the capital.
Bols: Though initially frightened by Bols' outward appearance, Wave eventually formed a strong bond with Bols, and saw the man's gentle nature behind his mask. Wave was strongly affected by Bols' death and was later seen bringing flowers to his grave, as well as offering help to his family. Overall, Bols' death deeply affected Wave. It caused him to swear to avenge Bols during one of Night Raid's attacks and he later attacked Syura, partially for killing Bols' family.
Run: As a fellow Jaeger, Run and Wave had a strong comradeship. Though not often seen together, the two cared about each other and Run comforted Wave after Bols' death. Run later also stopped him from getting into trouble with Wild Hunt, because Syura was the Prime Minister's son. Run later revealed his past and true intentions to Wave. After witnessing Run turned into a corpse puppet, Wave was greatly saddened by seeing his friend reanimated and enslaved and wished for Run to rest in peace instead. Later, Wave started studying in order to carry on Run's dream to change the Empire from within. Even in death, Run was still trying to help him and Kurome, which Wave noticed and was thankful for. Wave's feelings towards Run and Kurome gave him the strength and resolve to utilize Run's Teigu, Mastema, in combination with Grand Chariot.
Seryu Ubiquitous: Initially puzzled by Seryu's cheerfulness, Wave at first befriended her and was concerned enough about her well-being to want to comfort her after Dr. Stylish's death. However, he became more distant towards her after the latter revealed her psychotic nature. It was Seryu's psychotic nature that made Wave question the true nature of the Empire he served. However, he still cared for her and wanted to avenge her death at the hands of Night Raid, along with the deaths of Koro and Bols.
Dr. Stylish: Initially frightened by his effeminate nature, he warmed up to the scientist enough to consider him a comrade.
Syura: Wave openly detested Syura, mainly due to Wild Hunt's brutal methods during investigations, and Syura's abuse of his privileges as the son of the Prime Minister. He was further provoked by Syura when Wild Hunt tortured and killed the family of Bols, a deceased Jager. When Syura harassed Kurome and wanted to claim her as his new toy, the two men fought. Wave defeated Syura in hand-to-hand combat and humiliated him. While Syura wanted to kill him afterwards, he wasn't allowed to do so because Wave was a member of the Jaegers.
Tatsumi: While they only met briefly, Wave immediately warmed up to Tatsumi and liked him. He saw Tatsumi as the only other "normal" member of the Jaegers and he saw a lot of similarities between them. After stopping a fight between Akame and Kurome, Wave defected from the Empire. Wave and Tatsumi remained on friendly terms, complimenting each other's strength and resolve, and even admitted that they trusted each other despite being enemies.
Akame: During a battle with Akame, they both ceased fighting to talk and discovererd the other's bond with Kurome. However, Wave shocked Akame with his strong resolve to save Kurome's life while Akame wanted to end her suffering. When Wave ultimately saves Kurome, Akame saw him in a very favorable light and respected him for saving her sister, who she had given up on.
Najenda: Despite only meeting each other a few times, Najenda respects his decision and chooses not to prosecute him after the fall of the Empire. Instead she lets Wave live a quiet life with Kurome. She recommended him to keep Kurome company for the rest of his life and help her recuperate her health and personality. He wholeheartly accepted that offer.