more than red

A high school student with a reputation for being charming and flirtatious, Daiki, is known for his deep devotion to his older sister Futaba, whom he believes deserves the best. When he notices a quiet, reserved man named Kamiya spending time with her, he becomes suspicious and decides to investigate by entering her college. Confronting Kamiya, Daiki is relieved to learn he is not a romantic interest. Despite initial tension, the two eventually become friends. As they spend more time together, Daiki begins to notice a growing affection, realizing he feels a strong reaction whenever Kamiya shows signs of embarrassment.