Ginro is Kinro's brother. Strangely, despite not sharing a physical resemblance to each other and being vastly different in personalities to the point of being polar opposites, the two share a deep strong bond and understanding. They work together as guards, with Kinro being more responsible, while Ginro does his best to shirk his responsibilities or push them onto someone else. Kinro often lectures Ginro on being less lazy and shirking his responsibilities while Ginro thinks of Kinro as too straight laced and being a stick in the mud. Ginro on occasion also enjoys teasing Kinro or rubbing something in his face, such as stating Kinro's menacing look is due to him having blurry sickness and bragging how he was able to get a silver spear while Kinro, who had a golden spear that broke, wouldn't be getting a new spear anytime soon. Despite their differences, Kinro and Ginro clearly love each other.
When Senku builds a generator that needs two people to work in sync, he immediately looks for Kinro and Ginro as the two do manage to work together harmoniously to produce the energy Senku needs. When Kinro is heavily injured on a bridge with Hyoga's forces, he tells Ginro to cut the bridge with him on it so Hyoga's forces cannot cross the bridge, but Ginro refuses and breaks down crying, saying he could never sacrifice him. Similarly, when Kinro is turned to stone, Ginro is initially afraid of the intruders on their boat, but remembers Kinro was also turned to stone and tries to take his statue with him, refusing to leave him behind. He eventually is forced to as he realizes Kinro would want him to leave him behind to help Senku so that Senku could help rescue them all later. Kinro is later revived and once he learns Ginro acquired information that helps Senku at the cost of nearly dying before being petrified, Kinro is deeply worried for Ginro, but is proud of Ginro's accomplishment and promises to save him the same way Ginro tried to save Kinro.
Initially hostile and distrusting of Senku, due to him being an outsider, Kinro has since warmed up to the modern human. Observing his resolve, guts and nature, Kinro vouches for Senku once an outraged Kokuyo orders for Senku to be caught as he disrespected the village's traditions. Since Senku was named village chief, Kinro follows his instructions like are holy writ; he never questions or doubts anything Senku has him do, should it range from brute force or material scavenging. He has become grateful to the new chief who gave him glasses to correct his near-sight and help him fight better.
As he has gotten to know Senku, he knew Senku had devious intentions and suspected he was up to something when he was oddly nice to Luna.
Kinro gets along well with her, as they are both warriors for the village.
When he is wounded in the raid led by Hyoga, she wanted to assist him but her father held her back.
No interaction has been seen, though she was responsible for petrifying him and his allies on Ibara's orders. After her induction to the Kingdom of Science, Minami Hokutozai has taken notice of their similar serious attitudes. When asked what he thinks of Kirisame, he commented on her being a skilled warrior who is possibly stronger than him and that he would have to train harder to not lag behind.