The Ki-61 Hien started to reach front line units in 1942.
Deliveries started in February 1943.
The Ki-61 Hien was was used in New Guinea, the Philippines, Rabaul, and the Japanese home islands.
First Operational Sentais
The 68th and 78th Sentais received their Ki-61s in April 1943 while stationed in New Guinea.
The Chinese used captured aircraft in the Nationalist's air force.
In the summer of 1942 a Bf 109E, Ki-43-II, Ki-44-I, and a P-40E were tested against the Ki-61 and it outperformed all of them.
By the end of World War II there were 13 Sentais that were equipped with the Ki-61.
High Altitude Interceptor
The Ki-61 / Ki-61 II was one of the few fighters that could intercept B-29s at altitude.