NAKAIMO - My Little Sister Is Among Them!

Shougo Mikadono assumes the leadership of Mikadono Group after his father's passing. As part of his training to take over the company, he is required to marry a girl he loves from his new school by the time he graduates high school. He transfers to Miryuin Private Academy, where he is surrounded by several potential love interests, including Konoe Suruma, the class representative, and Miyabi Kannagi, a somewhat standoffish but kind girl. His task is complicated by the fact that one of these girls is his long-lost half sister, making it difficult for him to navigate his romantic feelings.