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to take the form of (esp. in ref. to a spirit, fox, raccoon dog, etc.); to assume the shape of; to turn oneself into; to transform oneself into
to disguise oneself as
to change radically; to metamorphose
to improve unexpectedly and dramatically (esp. of an actor, artist, rikishi, etc.)
彼は変装がうまくて別人に化けることができる。
He's good at disguises and can transform into another person.
お化けに化けて子供を驚かせました。
I disguised myself as a ghost and surprised the children.
化粧で別人に化けました。
I became a different person with makeup.