Japanese called it Hien (飛燕), U.S. called it "Tony"
Ki61-I Hei = キ61 飛燕一型丙 (fuselage mounted 12.7 mm (0.50 in) Ho-103 machine guns x 2 & the wing machine guns were replaced by Mauser MG 151/20 cannons. x 2)
Tony was the only mass-produced Japanese fighter of the war to use a liquid-cooled inline V engine.