Speaking with the US PlayStation Blog in a Metal Gear Solid retrospective, Kojima ended the interview with a tease for his next game, which will use the new Fox Engine.
"The Fox Engine is nearly finished, but the only way to be sure it works is to create a game at the same time and improve the engine with our tools as we go along," he said.
"Production studios in Japan are nearly extinct, a fact that we have recognised for nearly 10 years, and although the Fox Engine is not finished we are ready to show what it can do... on August 30 in Japan to be more specific."
Kojima added that originally Metal Gear Rising: Revengeance was planned to use the Fox Engine, but that changed when development of the title was moved to Platinum Games which is using its own internal engine.
Kojima's first game to use the Fox Engine currently goes by the codename 'Project Ogre'. Leaked title screen images at Comic-Con suggested that 'Project Ogre' may be the anticipated sequel Metal Gear Solid 5, though Kojima stated that the images were fakes.
Even if the Comic-Con title screen images are false, Kojima has not ruled out Metal Gear Solid 5 as the true identity of 'Project Ogre'.
Metal Gear Solid 5 was confirmed to be in development by Hideo Kojima last November.
The game is expected to be released between April 2013 and May 2014.
Metal Gear recently celebrated its 25-year anniversary. The original game in the series, Metal Gear for the MSX2, was released on July 7, 1987 in Japan.
> 'Metal Gear' retrospective: A look at Hideo Kojima's stealth series
Screenshot gallery - view images from the Metal Gear franchise below: