Local Wikipedia tells followings from Hiroshi Umemoto's book "Japanese army air force fighter units in World War II" -
The 85th Sentai
In early July 1944,
Began to updated the model to Ki-84. 4 were brought to Guangdong from Hankou.
As of August 1, the sentai owned 22 Ki-44s and 3 Ki-84s.
9 Ki-84s were added from Hankou soon.
In September 26,
the 22nd Sentai handed over 6 out of 9 Ki-84s to the 85th Sentai and returned to the homeland to prepare for the Philippine Air Battle.
In October,
85th Sentai fought well against the P-51B/Cs.
On October 4,
Captain Wakamatsu led 4 Ki-84s and 4 Ki-44s for patrol near Wuzhou when several P-51B/Cs of the US 76th Fighter Squadron attacked the ground. Wakamatsu and his team downed 4 with no damage on Wakamatsu side.
On December 18,
12 Ki-84s of the 85th Sentai and 13 Ki-43s from the 25th Sentai encountered a US large formation, including B-29s, in Hankou.
3 Ki-84s and 2 Ki-43s, including Wakamatsu's, were lost. Combined with AA fire, 4 P-51s, 1 P-40 and 1 B-29 were shot down.
On January 3, 5, 6 and 14, 1945,
Hankou air raid by the US. 85th Sentai and 25th Sentai intercepted. 6 were lost in action but, combined with AA fire, 8 P-51s and 4 P-47s were shot down.
On January 17,
The 85th Sentai and 25th Sentai intercepted P-47s. 1 each (total 2) were lost. 2 P-47s were shot down.
Ki-84 of 85th Sentai (front)