The Homare (Honor) was Japan’s most-used engine in the latter years of World War II. It had a very high specific output, incorporating for the first time in a Japanese engine, a steel crankcase, dynamic balancers, a dual magneto with a remote distributor (on the nose), and a nose sump pump. Its supercharger drive followed a Wright design, with a planetary reduction gear in series with the high gear for obtaining a lower compression ratio. All models suffered from unreliability, service difficulty (particularly when first entering service), and vibration.

The artifact powered the Yokusuka P1Y1 Ginga (Milky Way) (Allied Code Name FRANCES) twin- engine aircraft for low-altitude torpedo and dive-bombing attacks. Several of these aircraft carried out Kamikaze suicide attacks against American warships. This particular NK9C (Ha45-12) engine model also powered the Aichi B7A2 Ryusei (Shooting Star) single engine torpedo bomber (Allied Code Name GRACE), the largest and heaviest Japanese carrier-based aircraft to fly in World War II.