Masaki Sakamoto, seven years senior to his sister Rieko Sakamoto, shaped her moral compass as a mentor. His disappearance as a Kamikaze pilot during World War II left a profound void, fueling Rieko's dedication to music education as she channels his ideals and fervor through her teaching.

He surfaces only within Rieko's flashbacks and memories, embodying the enduring scars of wartime loss on post-war Japan. These recollections frame him as a bridge to traditional Japanese values, specifically the crucial preservation of Doyo songs—a vital root of cultural identity nurtured during recovery.

His permanent absence amplifies themes of mourning and the quiet resilience of survivors, reflecting wider societal challenges a decade after the conflict. Anchored solely in the past, Masaki undergoes no present narrative development. His influence resonates indirectly through Ms. Sakamoto's unwavering commitment to fostering student unity and pride via the choir competition.

Masaki exists solely within this narrative context, his characterization tightly focused on his historical role and symbolic weight within the film's exploration of national identity and reconstruction.