The Kabuki District's greatest mechanic. He wears a welding mask that covers his eyes, he has no hair and is recognized by a grey beard. His son's death left him with a deep emotional scar, and Takasugi took advantage of that and used him. He makes ugly and crude machines, and has a bad habit of telling important parts-of-a-messages later, which usually gets Gintoki mutilated. Now he is seen making machines and fixing Gintoki's bike.

His name is based on Hiraga Gennai.

Source: Wikipedia