Koichi (Sato) and Atsumi (Ayase) are childhood friends who have become lovers. Despite this closeness when Atsumi attempts suicide Koichi is at a loss to understand the circumstances that drove her to do such a thing. Now she is in a coma and Koichi needs to find out the reason. Since Koichi is a neurosurgeon he has access to the latest studies and so he takes part in a medical procedure that will allow him to enter Atsumi's subconscious. Through 'sensing', a type of neurosurgical procedure allowing contact with the intentional aspect of a comatose patient's mind, Koichi tries to discover why Atsumi tried to kill herself, and to bring her back to consciousness.
When he enters her mind she asks him to find a picture which she drew as a child. It is the key to a suppressed memory connected to a childhood trauma, an incident buried in their past which will bring their minds together and allow him to get close to truly knowing his love.