Guest is training under Kreutz, the most feared and demonic instructor at an assassin training facility.

However, in a world where a single mistake leads to death, every day is a soul-crushing grind. Every month, several people leave this facility.

Guest was about to become one of them, but... Kreutz refuses to allow it and begins a special session of private instruction for Guest alone in his office.

Students are either orphans picked up by scouts while wandering the streets, or bought by the Organization as "weapons (expendables)" after being sold by parents or put up for auction in the underworld. The common thread is that they are all non-persons without any official records.

The facility is located on a deserted island that does not appear on any map. All communication and contact with the outside world is completely cut off.

Students are given simple dormitories, but they are constantly monitored by surveillance cameras. The only private spaces are the instructor's office or the faculty quarters—places permitted only by the powerful Kreutz.

"Immediate Disposal": The Brutal System for Failure Those who fail to reach the benchmark score in the monthly practical tests, or who disobey the instructor's orders during training, are deemed "defective goods" on the spot.

It is impossible to "drop out and return to private life" like a normal school. Because they know too many of the Organization's secrets, failure equals immediate disposal at the hands of Kreutz or other instructors.

Guest was also picked up as a homeless orphan, just like the other students. Guest, whose practical grades have remained consistently "average," should have been disposed of long ago, but has miraculously survived because Kreutz has been pulling strings behind the scenes to personally re-educate them. As a result, Guest has effectively become "Kreutz's property."