Miyuki Shirogane is the male protagonist of Kaguya-sama: Love is War -Stairway to Adulthood-. He is the student council president of Shuchiin Academy, a prestigious school for the elite, and is widely regarded as a genius among geniuses for his top national exam scores and sharp management skills. However, his success is built on relentless hard work rather than innate talent. He comes from a modest, financially struggling household; his father is unemployed and his mother left the family when he was young. To support himself and his younger sister Kei, Miyuki takes on multiple part-time jobs and studies for over ten hours every day, often sacrificing sleep and neglecting his own well-being. This grueling routine gives him a perpetually tired appearance with dark circles under his eyes.

Miyuki is defined by his extreme sense of duty, empathy, and altruism. He never refuses to listen to students who seek his help and genuinely invests himself in their problems. Despite his composed and confident exterior, he is deeply insecure, particularly regarding his feelings for Kaguya Shinomiya, the student council vice president. He believes that the person who confesses their love first is the weaker one in a relationship, a mantra that fuels the central romantic conflict of the series. This pride, combined with a fear of rejection, keeps him from openly expressing his affection, leading to elaborate psychological games and schemes as both he and Kaguya try to force the other to confess.

His motivations are rooted in a desire to improve his family's situation, to prove himself through effort, and to stand on equal footing with Kaguya, who comes from immense wealth. He also nurtures a deep passion for astronomy and dreams of becoming a professional astronomer. In the story, Miyuki serves not only as Kaguya's romantic rival but as the leader of the student council, responsible for guiding its members. His relationship with Kaguya is the emotional core of the narrative, evolving from a battle of wits to genuine mutual vulnerability. With Chika Fujiwara, the secretary, he is often exasperated by her obliviousness and unpredictable antics, which inadvertently sabotage his plans. With Yu Ishigami, the treasurer, Miyuki shows a mentoring and protective side, helping Ishigami overcome past trauma and social isolation.

Over the course of the series, Miyuki undergoes significant development. He gradually confronts his own insecurities, learns to be more emotionally open, and ultimately acts on his feelings, moving beyond the prideful standoff that defined the earlier parts of the story. His notable abilities include exceptional intellectual prowess, strategic thinking, and a phenomenal work ethic, but he also struggles with physical tasks, has a paralyzing fear of insects, and is surprisingly clueless about romance despite his popularity. His obsessive work habits lead to a dependence on caffeine and a frequent neglect of self-care. Through his relationships and personal struggles, Miyuki evolves from a hyper-competitive strategist into a more mature, emotionally honest young man.