"Heaven" is an organization that utilizes Messengers of Death to ferry deceased souls to their afterlife. These messengers are sorted according to their proficiency, and Uka is classified as a "Rank C" dropout, despite her lackadaisical demeanor. However, she is unexpectedly paired with Tsumugi, an egotistical "Rank A" top performer. Additionally, Volume 1 of this manga includes the bonus chapters "Hane Oto, Kimi Oto."