A transformation or metamorphosis; changing appearance or form. Often used in fantasy, manga, or anime to mean turning into another form or disguise.
主人公が敵の前で変身して戦いを始めた。
The protagonist transformed in front of the enemy and began to fight.
彼は別人のように変身して、街を歩いていた。
He had transformed into someone else and was walking through the town.
変身後のデザインは子どもたちに人気だ。
The post-transformation design is popular with children.