Un:Birthday Song Ai wo Utau Shinigami is an adventure game that follows the story of Kanno Hotori, a girl who learns she has only one month to live. The narrative unfolds as two Reapers inform her about her impending fate, leading her to confront her mortality and make a poignant wish: to confess her feelings to her crush. This emotional premise sets the stage for a unique gaming experience that combines elements of fantasy and romance.

The game is designed for Windows and offers a full version license, ensuring players can fully immerse themselves in the storyline without limitations. Players navigate through various scenarios and make choices that influence the outcome of Hotori's journey. With its captivating plot and focus on character development, Un:Birthday Song invites players to explore themes of love, loss, and the significance of expressing one's feelings before it's too late.