Fake Sun

Fake Sun (偽太陽) is magic item in Mass for the Dead.

Description
A sacred treasure of a tribe of unique slimes, this item is used to suppress their abnormal transformations that occur when the moon shines. After the tribe was attacked by Chaos Beasts, only a group of five survivors managed to escape by using a Sealing Crystal that contained a teleportation spell that spirited them away to an area near E-Rantel. In unknown territory and the threat of night falling, the slimes wishing to avoid their violent transformation, activated their treasure in order to buy time to assess their situation. When their magic item brought day to night, it attracted not only the attention of the humans in the three, but also the Sorcerer Kingdom which was in the middle of launching their moon-viewing feast.

Appearance
The item is a small round jewel-like item.

Abilities
The item is not actually a sun, but a luminous gem that once active generates a photosphere around its core and then levitates high in the sky. It's main purpose is simply to "continue to illuminate the darkness of the night like daytime".

Its brilliance is so bright that it can simulate daytime. According to Mare Bello Fiore the artificial sun is just as good as the real one in providing light, but it doesn't produce the effect of raising temperature and so it likely does not affect climate or the growth of plants.

The artificial sun's effects can encompass a limited but large area. When it was used, the artificial day was centered around E-Rantel and spanned not just the Re-Estize Kingdom but also the Baharuth Empire, part of the Slane Theocracy, the Katze Plains and the southern part of the Azerlisia Mountains.

Trivia

 * The protagonist having found a unfinished novel by one of the Supreme Beings believed it was a prophecy as by sheer coincidence many parts of the story matched with the nightless night created by the fake sun.