It is the first week of April 1945. The Americans are bombarding Okinawa and have landed in their tens of thousands. But on a small island remote from the terrors of battle, 16-year-old Hiromi lives alone in a deserted house, day by day collecting star sand in little empty milk bottles left by primary school pupils.
Suddenly she comes upon a cave where American deserter Bob has appeared. Bob is taken in by Japanese deserter Takayasu, who tells Hiromi to leave, that nothing good can come to her by being with two deserters.
Hiromi’s father has gone to Nagasaki to work in a factory, and her mother, a Japanese-American, has remained in Los Angeles. She decides to look after the two men by bringing food to them, knowing that it is dangerous for them to be seen outside the cave. When Hiromi returns to where she is staying she finds Yoshigami, a native of the island who immediately takes an interest in her.
Soon after, Takayasu’s elder brother Hajime appears in the cave. He is severely wounded and can barely walk. Hajime, a fanatic soldier, vows to kill his brother, his enemy Bob and the treacherous Hiromi once he recovers from his wounds.
Hiromi returns to her home, where the real owner, Mrs. Gima has come back to. She tells Hiromi of the awful fate of her daughter.
As for the three men, they continue to live together in the cave, with visits by Hiromi, as tensions mount to what appears to be an inevitable climax of violence and murder….
We now find ourselves in 2016 in Tokyo, where a female student, Shiho, is instructed by her professor to write her graduation thesis about the war in Okinawa. The professor hands her a diary written by Hiromi. But the diary leaves some questions unanswered. Shiho’s curiosity leads her to the truth of what really happened to the three men in the cave …