Engaged to the Unidentified

All Kobeni wanted for her sixteenth birthday was to enjoy a cake with her family, but her mother surprised her with a piece of unwelcome news instead! The teen’s late grandfather arranged a marriage for the girl, and her 'fiancé' Hakuya, along with his mature-for-her-years little sister, are moving into the house today! Now, Kobeni and her pervy older sister Benio must adjust to their new extended family life, from figuring out what foods the newcomers dislike, to explaining to their friends who these new relatives are!