A rural village where it has been difficult for boys to be born since ancient times and there is a surplus of girls. In this village, there is an old custom - service - that has been in place since ancient times to ensure the survival of the village.
・Those who reach adulthood must start making babies from the night they reach adulthood. ・As a villager's duty, making babies is decided at a village meeting who will be their first partner. ・Men should inseminate as many girls as possible and girls should have sex with as many boys as possible and give birth to as many girls as possible.
Eita and Kana, who grew up together as childhood friends with birthdays just one day apart, also reach adulthood and are baptized into the village. Eita's first love, a young wife named Miku, is chosen to take his virginity and Nanami, who works in the next room and whom he admires as an older sister, joins in for fun and the three of them perform Eita's first service. However, it is not only Eita who is having his first service, Kana does the same...