Class de Ichiban Kawaii Gal wo Ezukeshiteiru Hanashi

Hori Kazami, a first-year high school boy, is busy talking about otaku things with his friends in the classroom, like usual. But he has a secret. Sakura Kouzuki, a model and the most popular girl in class, is his step-sister. They live together, and they are lovers. At school, Sakura tries to keep a reasonable distance from Hori and not let anyone know about her love for Hori and his otaku hobbies. But at home they are very much in love, watching anime, cosplaying, and eating Hori's home cooking together! "This stewed fish is delicious!" And so begins another fun evening between the two of them. (Source: HJ Bunko, translated)