Ano Hana ga Saku Oka de, Kimi to Mata Deaetara.

A fantastic encounter between a lonely modern-day girl and a Kamikaze pilot... One day, Kano Yuri, a girl in the second year of junior high school who is frustrated by her unchanging daily life, gets into a fight with her mother and runs away from home. Yuri spends the night in an old air-raid shelter in the neighborhood. The next morning, she wakes up and sees…!? (Source: Pixiv Comic, translated)