In August 1944, while a POW in rural New South Wales, Toyoshima was one of the instigators of the Cowra breakout, sounding a bugle to signal the commencement of the escape, and died during the fight.

He is known (from Japanese records) to have flown in air patrols from Hiryū over the carrier fleet during the raid on Pearl Harbor.

[14] From the outset of captivity, he actively sought to learn English, both from soldiers, local internees, and friendly guards.

[8] One Melbourne guard, a former policeman called Sam Shallard, stayed in contact with Toyoshima through letters after his move.

[4] Toyoshima arrived at the Cowra POW camp on 8 January 1943, and his airman status and developing English skill soon allowed him act as a leader and translator.

[16] Later, as many more Japanese POWs arrived, tensions increased due to overcrowding and power shifted towards the army and Toyoshima became a deputy leader.