Panic World(1971)

Takashi Shiki is a ronin student who has nothing going for him. One day, he sees fighter planes flying above the sky - as well as a man who died from a gunshot to the head on the ground. The next day, after tanks start to show up, a mysterious young woman named Yuki Kitano begins to accompany Shiki. Shiki also is given the task of watching over his wealthy neighbor's mansion for a hefty sum. But this fortunate turn of events for Shiki is too good to be true: before long, the truth of the matter becomes clear to him - World War III is about to begin.