Slang abbreviation of 陽キャラ. Refers to someone with a bright, sociable, and energetic personality, often contrasted with 陰キャ (gloomy/introverted person). Common in youth and internet culture.
Which is better, a cheery person or a gloomy person?
ヨウキャ
kana-only spelling
Katakana spelling used in casual or stylized writing.
Etymology
Abbreviation of 陽キャラ (yōkyara), itself a blend of 陽 (yō, 'positive, bright') and キャラ (kyara, from English 'character'). The term emerged in Japanese youth slang and internet communities.