Darwin

Ranmaru is a 450-year-old vampire who works in a bathhouse. As a vampire he is particularly picky about his blood choices, his main goal being to drink the blood of an 18-year-old virgin. To do so, he has been watching 15-year-old Rihito, the son of the bathhouse owner who saved him from near death. Rihito must not lose his virginity before he turns 18 and Ranmaru does everything he can to prevent that. However, when Rihito starts to show interest in a classmate, Ranmaru's desperate fight to preserve the boys virginity begins.

Yuri is a high school student in the present day. She isn't happy with her life at home or school. One day, she has an argument with her mother and runs away from home. Somehow, when Yuri later opens her eyes, she realizes that she is in the year 1945. She happens to meet Akira. He is a pilot for a kamikaze unit in the military.