An Event Weapon Imitation (模倣事象兵器 Mohō Jishō Heiki, localized as Artificial Causality Phenomenon Weapon) is an imitation of the Arch-Enemy Event Weapons created through the power of science by Kokonoe Mercury. It is a prototype version of the Idea Engine.
Unlike the Event Weapons, which are living beings with a soul, these are built mechanically, making their power lower than that of an Event Weapon, but also more stable. Their resistance to Event Interferences is unstable, and Kokonoe continues adjusting it.
Both the Event Weapon Imitations and the Idea Engines are said to be Observationally identical in their nature.