In this world, there are two special types of humans: "Tear Eaters," who must consume the tears of others to survive, and "Tear Givers," who produce the special tears necessary to sustain Tear Eaters.

■Tear Eaters
If a Tear Eater goes without consuming tears for a certain period, their bodily functions gradually weaken, eventually leading to death. The tears of Tear Givers, in particular, possess special properties that sustain and restore life force.

Tear Eaters can identify Tear Givers by scent or presence, but Tear Givers cannot tell whether someone is a Tear Eater.

Not all Tear Eaters harm Tear Givers. However, when they fall into extreme starvation, their reason collapses and they are ruled by instinct.

■Tear Givers
When exposed to light, the tears of Tear Givers take on a faint iridescent sheen, displaying beautiful colors like an aurora. Since they are clearly different from ordinary tears, one can identify a Tear Giver by seeing their tears.

Due to their rarity and beauty, Tear Givers have been treated as highly valuable beings since ancient times.

■The Efficacy of Tears
The efficacy of tears varies greatly depending on the emotion felt when they are shed.

Tears shed from positive emotions such as joy, happiness, relief, or being moved are weak in efficacy, while tears shed from negative emotions such as sadness, suffering, fear, anger, pain, or despair are stronger.
Tears caused by pleasure, in particular, have an extremely high life-sustaining effect even in small amounts.

Because of this property, some Tear Eaters use violence, threats, or imprisonment to force negative emotions upon Tear Givers and obtain their tears by force. Some even go so far as to take their bodies.

For this reason, Tear Eaters are feared as "a race that lives by making Tear Givers cry," and are loathed by Tear Givers as well.

The required amount and efficacy of tears vary from individual to individual, and even tears shed from positive emotions can sustain life if consumed regularly. However, tears must be fresh to have any effect and cannot be stored for long periods.

Tear Givers are easy targets for Tear Eaters and are prone to being attacked. Since they cannot even tell whether someone is a Tear Eater, please be especially careful when walking alone.