Dictionary / Vocabulary / 化けの皮
ばけのかわ
mask (concealing one's true character); disguise; sheep's clothing
Also written 化の皮
彼の化けの皮をはごうとしたが、むりだった。
I tried in vain to catch him out.
ついに化けの皮を剥いだ。
Finally he showed his true colours.