The Ki-109 is based on the Mitsubishi Ki-67 heavy bomber, refitted as an interceptor in an attempt to counter the American high-altitude bombing raids that devastated Japan. It is armed with a 75 mm anti-aircraft gun modified for aircraft use, and almost all defensive armament from the bomber version has been stripped, except for the tail turret, to maximize performance.

This bomber-interceptor was introduced in Update 1.71 "New E.R.A.". Its 75 mm gun is effective against bombers but should not be used on agile fighters or fast-moving vehicles. The Ki-109's defensive armament is poor, and conflicts with fighters should be avoided at all costs. Alternatively, the 75 mm gun is also effective against tanks if a clean hit can be obtained.