Osananajimi no Onee-chan Sensei to H de Naisho na Kankei!?

Keita and Kuka are childhood friends, their house is right next door, and they have loved each other since childhood, but have never been told.\ Eventually, when Yuka became a college student, she left home and the two separated, but she decided to intern at the school where Kaita attended, and returned to her hometown during that time.\ On the first night, Kuka came to Keita's room and said, "I want you to be my first person, but isn't that great?"\ Keita's desire, suppressed by the words, exploded, and the two crossed the line.\ A twisted love story between two people who can't tell each other even if they have two feelings begins ......!