When he was the commander of a unit in Rabaul on New Britain he suggested modifying the ordnance fitment of the Nakajima J1N as a night fighter, which by 21 May 1943 was successful against B-24s and B-17s, although less so against B-29s.

[1] Kozono was in command of Atsugi Aerodrome during the latter part of the Second World War, and initially refused to surrender.

They printed leaflets and dropped them over the Kanto area calling for the war to be continued "to the end".

[2][3] Weakened by malaria, Kozono was one of 70 soldiers to be arrested by the Imperial Japanese Navy for continuing to fight.

Yasuna Kozono was portrayed by Jun Tazaki in the 1967 film Japan's Longest Day.