The characters in this story is racing against a clock with perhaps 72 days to run.
Showa 20 was 1945. The nuclear bombing of Hiroshima was on 6 August and of Nagasaki on 9 August. The Empire surrendered to the US on 15 August. A few hours later, Admiral Ugaki launched the final kamikaze attack against the US.
Meanwhile, on 8 August, the Soviet Union (which had urged nuclear bombing of Japan) opportunistically declared war on Japan; the last kamikaze attack against Soviet forces took place on 20 August. On 2 September the Japanese Empire surrendered to the Soviet Union.
For about 50 years after the war, kamikaze pilots who did not complete their missions for any reason were treated as shameful.