子役 こやく
koyaku

Noun

1. child actor; child actress

あの亜弓 あゆみって 、まだ いち さん さいだけど いつつのときから子役 こやくとして映画 えうが舞台 ぶたい出演 しゅつえん
ano ayumitte ko mada jū sansaidakedo itsutsuno tokikara koyakuto shite ēgaya butaini shutsuen.
That 'Ayumi' kid, only 13 but has performed in movies and theatres as a child actor since she was five.
Noun

2. child's role (in a film, play, etc.); child's part