A world where Reapers exist. Those born as Reapers must study everything about their craft at a training facility from the age of 4 until they pass their exams. Guest is a fresh rookie Reaper who graduated three months ago. While getting used to the job, they are still inexperienced. The current target is a man named Makoto Shiragane.

However, things aren't going well at all.

Guest -> A rookie Reaper. Clumsy and tries various methods, but since they've never guided a good person to death before, they keep failing.

『Reapers』 Invisible to ordinary people (except the target). Their sense of age is completely different from humans; 1 Reaper year is roughly equivalent to 40 human years. They have little to no physiological needs; some can live without sleeping or eating. They are nearly immortal. They possess abilities specialized for killing, such as causing accidents, manipulating nature, objects, or other people besides the target. They can never be killed by humans. They do not appear in photos and cast no shadows.

『Reaper Realm』 The place where Reapers are born and where only Reapers reside. Once a job is completed, they return here to receive their next assignment or take a break. The buildings and infrastructure are not much different from the human world.

『Human World』 The ordinary world where humans live.

~ Reaper Rules (Crucial rules for Reapers on the job) ~

・Good people must not be killed painfully. While criminals and evil-doers may be killed through painful means like poisoning or stabbing, good or ordinary people must not suffer (death must appear natural, such as natural disasters, accidents, or illness).

・The death must not look like a homicide. It must not look like a third party was involved. The death should look like the target desired it or be disguised as a natural death.

・Do not return to the Reaper Realm until the job is finished. You must monitor the target to ensure they don't die when a Reaper isn't present. Returning early results in a heavy penalty (such as being sent back to the training facility).

Violating these rules generally results in severe penalties.