It entered service in 1944, but saw limited action. The main type (102b) was kept in reserve to protect Japan, although it did see some limited duty in the Okinawa campaign. It was kept out of front line service because it was hoped that it would be the carrier of the Igo-1-B air-to-ground guided missile when the Allied invasion of Japan occurred.
Externally similar to the 102b, but with turbosuperchargers that enabled the engine to maintain its rating at higher altitudes. 57 mm (2.24 in) cannon was swapped in favor of a 37 mm (1.46 in) cannon, and the 12.7 mm (.50 in) rear gun was deleted, 26 built.
Ki-102b (Type Otsu)
Ground-attack variant similar to prototypes, except with revised tail wheel, 207 built.
Ki-102c (Type Hei)
Night Fighter version with lengthened fuselage and span. Radar under a Plexiglas dome, oblique-firing 20 mm cannons, and the 20 mm cannons in the belly replaced with 30 mm (1.18 in) cannons completed the package, 2 built.
High-altitude fighter prototype with pressurised cabin, two conversions from Ki-102b aircraft using the structural improvements used on the 102c.
Improved version of the Ki-108 with longer fuselage and enlarged wings. Two built.