A high school freshman named Himari Uehara finds himself clueless about matters of intimacy, lacking guidance due to his absent father and missed health classes. His confusion peaks when he wakes up to a peculiar situation with no one to turn to. Fortunately, a newfound friend at school, Gaku Asada, steps in to fill the gaps in Himari's knowledge, offering to enlighten him on all the subjects he overlooked in health class and beyond.