outer layer; veneer; one skin
Literally 'one skin/layer'; often used figuratively for a surface appearance that hides the true nature. Common in the idiom 一皮剥ける (to shed one's old self and mature).
See also: 一皮むく
His kindness is just a veneer; underneath it's pure calculation.
Having shed his old self, he is much more confident than before.
Standard kanji spelling; common in news and everyday writing.
Kana spelling is sometimes used for clarity or in casual writing.
Compound of 一 (one) and 皮 (skin, peel). The figurative sense comes from the idea of peeling off one layer to reveal what is underneath.