A 16-year old sophomore student who was often bullied in school and was a hairs breadth from snapping, Kohta is a gun otaku (enthusiast) and knows the ins and outs of the firearms and any military-related equipment that the group comes across. At the beginning of the story he helped Saya Takagi escape danger, though only did so by following her orders. His skills as a marksman have proven to be a valuable asset to keeping everyone alive. On a one-month trip to America he was trained by the US military contractor Blackwater USA which furthered his obsession over weapons. In addition to being the gun expert and marksman, Hirano also helps train Takashi and the others in the use of firearms. Also, now that "normality" no longer exists, Hirano feels that he is free to vent the repressed rage he had against those who bullied him, and as a result has become more self-confident. He claims to have come from a very prestigious family, with his father working in jewelry business, his mother a fashion designer, his grandfather a captain of a ship and his grandmother a violinist.