Shōgo Kaga is a first-year student at Chihaya University. His unresolved romantic past with Kanata Kurosu, who left abruptly without explanation, colors his life. Her unexpected reappearance at his relaxation spot, Cubic Cafe, instantly creates tension with his current girlfriend, Neo Kashima.

Shortly after Kanata's return, the accidental death of Cubic Cafe manager Tanaka during an outing with her becomes a pivotal crisis. This event profoundly impacts Shōgo, worsening his emotional instability. He struggles with grief and confusion, withdrawing and neglecting Neo's concerns about their relationship. Neo fears he might rekindle his past with Kanata, especially as he comforts Kanata during their shared mourning.

Shōgo confronts these compounded challenges. Interactions with secondary characters, like Neo's sister Mifu and Yue Imasaka, offer perspectives that gradually shape his decisions. During the Christmas season following Tanaka's death, he reaches a resolution: he openly reaffirms his commitment to Neo, choosing to move forward with her instead of returning to Kanata. This decision prompts Kanata's departure for America, concluding their unresolved relationship. Shōgo's journey reflects a transition from passivity and emotional confusion toward decisiveness in his personal relationships, framed by themes of loss and reconciliation.