Also known as: モンスター化, 人魚化, スライム化, 魔物化, 人外化, モンスター娘化, 魔物娘化, ラミア化, ポケモン化, 妖精化, サキュバス化, ドラゴン化
When an otherwise normal human character is transformed into some kind of monster-like character such as a Mermaid, Centaur, Lamia, Slime Girl or similar.
The complete opposite of this is Humanization.