Twilight

Twilight (黄昏, Koukon) is the title given to the children and descendants of those who used the Celebrer drug. While Ergastulum was created to control and house Twilights due to an influx of them after the war, they are still a source of controversy. Anti-Twilight factions are prominent in the city despite pro-Twilight support from three of the four Big Fathers.

From birth, they are registered and controlled using tags embedded with chips that monitor their vital signs. Thus, they are also known as "Tagged". These tags also have their rank - speculated to be a measure of the Twilight's strength - with D/5 (the default) being the lowest and S/0 the highest. After a Twilight's confirmed death, they are automatically deleted from their category and their family registration. Every record of their existence is erased.

The Three Principles
Twilights are required to follow three main principles: Those who don't follow the principles are severely punished.
 * Article One: Twilights must not intentionally hurt humans. Destroying the overall balance by disregarding this rule is forbidden.
 * Article Two: Twilights must obey orders directed to them by humans. However, orders that conflict with article one are exceptions.
 * Article Three: If the situation does not conflict with articles one and two, a Twilight must defend oneself.

Biology
All Twilights possess enhanced abilities due to their predecessors' use of Celebrer. They are noted for being incredibly violent and destructive; Twilight mercenaries are often hired due to their effectiveness in battle and one of the four big houses, the Paulklee Guild, offers its Twilight members as hired guns. It is speculated that Twilights are grouped into certain "types" depending upon their forté. Marco observes that, like Galahad, Mikhail seemed to be a "power-type", and Ginger is noted for her incredible speed.

However, Twilights are riddled with sometimes multiple mental and physical disorders, known as "compensation", which is hereditary. Along with these deficiencies, the lifespan of a Twilight is drastically shortened, usually ending in their early thirties. There are more cases of severe compensation with those who have a Twilight mother as opposed to those with a Twilight father.

Hagure (日暮れ) is the title give to the children of a Twilight and a normal human. They have less severe compensation, less required intake of Celebrer and slightly longer lifespans due to their normal parent. There are records of some living to be 49 years old.