Summary Only I Know from Kainu Manga
Only I Know summary: Due to certain circumstances, Heike Waku transfers to a new high school. There, he meets a very cool classmate named Oura-san. With a famous model for a sister and a face that never smiles, she seems like a distant and untouchable presence... or so it seemed. But by chance, Waku happens to catch a glimpse of Kouri-san’s dazzling smile. In that moment, his world changes completely! For that smile… I’ll do anything!! From Taamo, the creator of House of the Sun, comes a heart-pounding, grin-inducing high school romance!