"Sakura" of the Kirishima family and "Hayaba" of the Tachibana family have a tradition of betrothing children from each generation. Sakura, who accepted this custom, noticed that Hayaba, who was younger than her, was interested in female bodies, so she let him touch her G-cup breasts and fondle her crotch. Then the next day, the two welcomed their premature first night together…
