This character changes appearance with a henshin.
Henshin is the Japanese word for "transformation", literally meaning, "to change or transform the body." This word is primarily used in manga, anime, and tokusatsu dramas for when a character transforms into a superhero. Henshin heroes usually have a "henshin call", a catchphrase which they recite when they transform.
This trait is intended for characters that transform but retain their nature, so while it is valid for a human to human transformation, other forms are covered by shapeshifting and metamorphosis.