Wiktionary
uchi-deshi
n. In Japanese martial arts, a live-in student or apprentice who trains under and assists a sensei on a full-time basis.
Wikipedia
Uchi-deshi
is a Japanese term for a live-in student/ apprentice who trains under and assists a sensei on a full-time basis. The system exists in kabuki, rakugo, shogi, igo, aikido, sumo, karate and other modern Japanese martial arts.