Set in a future where research is being conducted on male pregnancy to combat the population decline, Nagisa Fuyumi finds himself unwillingly turned into a test subject. Despite being at the institute for five years, he has never experienced pregnancy. While enduring this grim existence, he encounters his childhood friend, Hayato Hinozaki, who he once admired and has fallen for again. However, their reunion occurs under the circumstances of his role as a test subject and Hayato's position as a researcher…?