Megumi Aso
Megumi Aso is a famous model and the daughter of Yuri living in the year 2008, born on December 29, 1987. As a Fangire Hunter and as Yuri's daughter, Megumi makes it her duty to hunt down the Fangire as well as finish her mother's unfinished affairs, such as the Rook. She meets Wataru and develops a liking towards him after helping him with his allergy issue, unaware that he is actually Kiva himself. She is also not afraid to tell him off whenever he acts strange. While Keisuke Nago has expressed his interest in her, Megumi cannot stand him and was reluctant to notify him of Kiva's reappearance. Her weapon is a rather small pistol that shoots slugs at high velocities, with an attachment which shoots out a chain that resembles her mother's Fangire Slayer. It seems that she shares her mother's cynophobia. Over time, she starts to see Kiva in a different light as he continues to fight the Fangire, rescuing her on more than one occasion in the process. When her younger brother named Mitsuhide Aso, the Fangire Hunters' benefactor, comes to reclaim his sister, Megumi refuses to leave and convinces her brother to let her remain after destroying the Rook using the Ixa System. When Shima orders the elimination of Kiva, together with Nago she tries to assassinate Kiva but cannot do it. After Kiva's Fangire blood reacts he jumps on the bridge and grabs her and was going to kill her when Nago intervenes leading Kiva to regress back to Wataru to her shock. Back at his house she, Shizuka and Nago try to cheer Wataru up but to no luck. Megumi, along with Ryo Itoya, are the only two of the 2008 Ixa users not to use the Rising Ixa form. After Nago's eyesight was failing, Megumi encouraged him to continue as Ixa when he considered quitting the Wonderful Blue Sky Organization. After the final battle was over, she would marry Nago a few days later. After marrying Nago she tried to fight the future threat with her husband and the other Riders only to be stopped by the guests for fear of ruining her dress.
Shizuka Nomura
Shizuka Nomura is a 14-year-old girl who able to get around the shyness of Wataru being a motherly figure to him as he teaches her how to play the violin. She seems to be infatuated with Wataru; as a result, she can be jealous of other women in his life and actually sabotages his relation to Mio. Shizuka happens to be one of the few people to know about Kivat, and eventually Tatsulot, though she does not know that Wataru is Kiva, though by the last episode she does. She is also shown to be very adept at drumming.
Kengo Eritate
Kengo Eritate is an independent rock guitarist and vocalist from Tokyo who lied about coming from Osaka out of shyness. Although he formed a band called IKEMENS, other members got tired of his character and dropped out. After that, he makes Wataru and Shizuka join and aims at the major debut as a new IKEMENS as part of his lifelong dream to be a rockstar. Though he learns that Wataru's lifelong dream is not like his, Kengo remains Wataru's friend as the two promise to help each other out with their dreams. However, when nearly devoured by the Rhinoceros Fangire, Kengo encounters Kiva and begins to idolize him and then Keisuke after seeing him fight the Ladybug Fangire, wishing to be the latter's apprentice. When he is deputized as a temporary Fangire Hunter, Kengo has to be hospitalized after shoulder and hand injuries from fighting the Crab Fangire. Once released from the hospital, he learns that due to his injuries, he can no longer play the guitar, and as a result, gets angry at Wataru from hiding this truth from him. The rage gets worse when Kengo overhears Nago naming Wataru his apprentice instead of him, with Kengo being taken Shima's wing and made into an official Fangire Hunter, now bitter and harsh with no respect for Nago and very distrustful of Wataru. When Nago is injured in action, Kengo eagerly takes his place as the Ixa System's user. However due to the incident where Kiva's Fangire nature takes over, Kengo is forced to return the Ixa System back to Nago after he attempted to redeem himself by fighting the Seamoon Fangire and almost getting killed by the Bishop. Kengo, in a last-ditch effort to bring back Wataru to battle, plays his guitar with what ability he has left and then begs Wataru to come back, apologizing for his recent behavior. At first, Wataru initially refuses, stating that he can't be friends with anyone due to his heritage, but after Wataru returns to being Kiva, he relents and both he and Kengo become friends again. He later is a guest in Nago's wedding and helped carry the presents to the wedding.
Mio Suzuki
Mio Suzuki is a meek and clumsy girl born in 1989 who fell in love with Wataru after they meet at her previous job at a restaurant, where she was fired for being clumsy. However, her encounter with Fangires reveal that she is actually Maya's successor to the title of Queen of the Checkmate Four and the future bride to Taiga, donning an anklet from the Bishop to complete to her full transition into the Checkmate Four. Though in charge of killing traitors, which she has been reluctant to carry out, Mio is given the additional task of killing Kiva to protect their kind from him. Though she was unaware that Wataru is Kiva at first, still having feelings for him in spite of being forced to marry Taiga. After finding Maya and learning she can't rid herself of the title easily, she admits to Taiga she has no love for him before she learns that Wataru is Kiva. Learning that Wataru was half Fangire, she tries to convince him into defeating Taiga and taking his place as the King of Checkmate Four so they can be together. But when Wataru declines her request, Mio attempts to kill Taiga herself after faking that she wants to marry him. However, in spite of this, Mio tries to stop the fight between Kiva and Saga, knocked away from the two as Bishop takes his chance to fatally wound her for her earlier action. On the verge of death, Mio gives Wataru the ring he gave her during their early dating, and he puts it on her finger before she crystallizes and shatters. Mio appears to Wataru as a spirit from the shard he kept as a memento before Wataru traveled to 1986, encouraging him to live on and giving him closure. Just like her predecessor Maya, Mio can transform into the Pearlshell Fangire and can utilize all of the previous Queen's powers, though she can turn day into night with a violet moon in the background and her Fangire form is indigo compared to Maya's being a pink color.
Otoya Kurenai
Otoya Kurenai is Wataru's father who battles the Fangire menace in 1986, his ideology that "All humans are music" his reason of fighting Fangires was to protect that music. Otoya is a ladies man who retires from being a professional violinist for reasons unknown. It is by accident that he interferes in Yuri's mission and is eventually brought into their group as a result. Though normally a casanova, Otoya is vexed on anything marriage related, things always staying the same, and others getting in his way. He was the first to learn Jiro is actually a Wolfen, although no one believes him until later when Jiro threatened Yuri and reveals himself. He then becomes the second user of the Ixa System when Jiro was exposed. He is also capable of reasoning with a Fangire, as he befriends Omura/Frog Fangire and convinces him not to harm others. It seems that he won't destroy Fangire who are non-threatening to humanity. During his battle with the Fangire Race, Otoya falls in love with Maya, the original Queen of the Checkmate Four, resulting in the chain of events that led to him becoming the second Dark Kiva after forming a pact with Kivat-bat the 2nd to take on the Fangires' King. Otoya, along with Wataru, succeed in destroying the King. He would then pay final visits to Yuri, the Arms Monsters, and Maya before finally dying in Maya's arms after playing her favorite song. He would leave behind the Bloody Rose, a violin that Otoya himself made with Maya's help, for Wataru. However, in a strange turn of events in 2008, Otoya's spirit makes his appearance when he suddenly finds himself in Wataru's body. During that time, he recognized Megumi and Kivat as the children of those from his time. He also starts building a new violin with Wataru unaware that his father is building it through him. He would appear to Wataru in spirit one final time, encouraging his son not to give up as he lives on through him.
Yuri Aso
Yuri Aso is the founding member of the Fangire Hunters 22 years ago, meeting Otoya by sheer accident. She hates the Fangires with a passion, referring to them as "God's mistakes", as it was the Checkmate Four's Rook who murdered her mother Akane Aso, one of the founding members and designer of the Ixa system. However, her revenge on the Rook was never resolved though she did succeed in providing her daughter an advantage and finally was being able to move on after defeating the Rook personally. After admitting her feelings for Otoya, she moved in with his house to live as his roommate, only to feel betrayed when Otoya is seeing Maya. But once learning of Maya's identity, Yuri starts to track her down with intent to kill her, but after learning that Otoya loves her, she decides to give up and breaks up with him after rescuing him from the King. Otoya would see Yuri one last time to say some parting words before his eventual death from usage of the Dark Kiva power. Yuri seems to be cynophobic, which can be a hassle while she is working at the Cafe mald'amour; however, she seems to have gotten over this fear as she went out to search for Kido's dog, Buruman, on a rainy day. Her weapon consists of two bars that connect together to create a short snake sword named the Fangire Slayer which is capable of elongating. However, by 2008, Yuri is deceased and buried next to her mother. She would appear before her daughter in spirit to congratulate her on her marriage to Nago.
Mamoru Shima
Mamoru Shima is a mysterious millionaire who is the president of the Shima Foundation, a front for the Wonderful Blue Sky Organization that funds the Fangire Hunters, spending his spare time at a gym. He also gathers information on any new members of the Fangire Race that the Organization comes across, as well as seeing Kiva as a possible greater threat due to the original's rampage in 1986, believing from his experience with his foster-son Taiga that Fangires and humans cannot co-exist. He let Kengo be part of the organization, training him to be a more suited successor to Ixa System, but fires him after Wataru runs away. It was soon after that Shima suffers an ironic fate when mortally wounded by the Sungazer Fangire and made into a Fangire by Taiga to save his life, forced to turn toward Wataru to be his bodyguard. But after revealing to Wataru the relationship between him and Taiga, Shima attempts to kill Taiga only to be defeated by Saga and taken away to heal his wounds. Shima eventually returns to aid his friends in the Wonderful Blue Sky Organization's final battle against the Fangires. Shima also talks about Wataru's father, Otoya, who he deemed "unique" and how Maya entrusted Taiga to him in order to prevent any retribution in the future. At the end of the series he attends Nago's wedding, retrieving the presents along with Kengo.
Akira Kido
Akira Kido is the owner of the Cafe mald'amour and an acquaintance of Otoya's in the past, a rival with Shima in who can lose the most weight in 1985. He owns a Golden Retriever named Buruman, a puppy in 1986 and a fully grown dog in 2008. He is the first few to know that Wataru is Otoya's son. Akira and Otoya do not get along, although Buruman took an instant liking to the violinist. Akira was also a fan of the popular at the time song group, Onyanko Club. In the aftermath of the final battle, while Buruman was staying at a vet, Akira took in a black Pug named Sayuri.
Series:  Kamen Rider Kiva