陽キャ
Youkya
ようきゃ
Short for 陽気なキャラクター (youki na kyarakutaa — "sunny/cheerful character"). Describes someone who's bright, sociable, and naturally good with people. The opposite is 陰キャ (inkya — "shady character," i.e. an introvert). Originally internet slang, it spread among students and is now used across age groups. The youkya/inkya binary — sorting people into "extrovert" or "introvert" camps — is a distinctly Japanese youth culture phenomenon.
Examples
あの子は陽キャだから誰とでもすぐ仲良くなれる
She's such a youkya — she makes friends with anyone instantly.
Talking about a classmate
陽キャのフリするの疲れるわ
Pretending to be a youkya is exhausting.
Being honest with a close friend
陽キャか陰キャかって聞かれても困る
When someone asks if I'm a youkya or inkya, I never know what to say.
大学デビューで陽キャになろうとして失敗した
I tried to reinvent myself as a youkya in college and totally failed.