Kimi no Suizou wo Tabetai opens with a withdrawn, unnamed high school student who keeps to himself and expects little from the world around him. His quiet routine changes when he finds a handwritten diary called Living with Dying and discovers that it belongs to Sakura Yamauchi, a cheerful and popular classmate who is secretly living with a terminal pancreatic illness. Because only her family knows the diagnosis, Sakura chooses to spend the time she has left beside someone who will not treat her with pity, and the boy who would rather stay invisible becomes her unexpected companion.
As Kimi no Suizou wo Tabetai unfolds, Sakura's warmth, energy, and honesty slowly pull him out of isolation, while his steady, understated presence gives her a rare chance to enjoy ordinary days without masks or obligations. The film builds its emotional force through small conversations, shared routines, and the fragile comfort of simply being seen. Rather than chasing spectacle, it focuses on the quiet ways two very different people shape each other's lives, turning a brief relationship into a poignant meditation on connection, mortality, and what it means to live meaningfully while time is running out.