Kengo’s Japanese father runs the Sunflower Diner in Azumabashi, and his mother is Russian. It is his sister Olga who has inherited the majority of their mother’s Russian traits.
Kengo is generally a gentle soul and finds himself easily swayed and pushed around. He is deeply suspicious of the hIE, and participates in the Antibody Network, an organization that isn’t above resorting to violent tactics to achieve its anti-hIE agenda. Despite this, he is a loyal friend to Arato, and when Lacia is abducted, he helps Arato out by feeding him information from the Antibody Network in order to help Arato try and track down Lacia’s kidnapper.