Kurumi faced profound grief after her boyfriend Hal died in a sudden airplane accident. She withdrew completely, ceasing to eat, sleep, or interact with the world, becoming reclusive. Her grandfather initiated robot therapy, deploying a humanoid robot designated Q01, designed to resemble Hal, to help her cope and move forward.

Initially resistant, Kurumi gradually responded to the robot's presence. Taking Hal's appearance, Q01 worked to understand Kurumi's wishes by solving messages she had written on a Rubik's cube. These messages revealed desires like wanting a pet giraffe or wishing to attend a festival in a yukata. Fulfilling these requests helped Kurumi slowly re-engage with life, culminating in her agreeing to join the robot for the festival.

During the festival, Kurumi wrote a new message on an unused side of the cube. This moment coincided with a pivotal revelation: the airplane accident actually claimed Kurumi's life, not Hal's. The grief-stricken Hal had suppressed this truth, leading to a psychological reversal where he believed Kurumi had died. The "Kurumi" interacting with the robot was Q01 assuming her form as part of Hal's therapeutic intervention to confront his loss.

The real Kurumi had argued with Hal before her flight over his hidden financial struggles and involvement in risky activities, leading her to board the plane in anger. Her written wishes on the Rubik's cube, discovered posthumously, served as a conduit for Hal to process his grief. Her final message, revealed after the festival, expressed enduring love.

Kurumi's influence persisted through these artifacts, aiding Hal's journey toward acceptance. The act of him speaking to her while eating alone at home signified his gradual healing, acknowledging her absence while finding a way to live on.