Masashi Satou is a supporting character in the anime To Heart: Remember My Memories. He is Hiroyuki Fujita's closest friend and has known him since childhood, along with Akari Kamigishi, with whom he attended kindergarten and junior high school. Masashi carries a peaceful and quietly optimistic demeanor, often serving as the calm voice that defuses arguments or tense situations among his peers. Despite his easygoing and soft-spoken nature, he is notably skilled at sports, particularly football, and is actively involved in his school's soccer club. His friendly personality makes him well-liked by classmates, and he maintains solid academic standing. Masashi has an older sister and keeps pet hamsters as a hobby.

Within the story of Remember My Memories, Masashi continues to play the role of a loyal friend to Hiroyuki and the wider circle that includes Shiho Nagaoka. He is a member of the soccer team and is often busy with club activities. His motivations revolve around supporting his friends and navigating his own personal challenges, such as the prospect of studying abroad and the financial concerns that come with it. Over the course of the series, Masashi shows development when he confesses his feelings to Akari, adding a layer of emotional complexity to his character and affecting the dynamics among the main group. His notable abilities include his athletic talent, his knack for maintaining harmony in the group, and his inherent reliability as a stabilizing presence.