coach attached to another stable
Sumo term: a coach (親方) who is formally affiliated with a stable (部屋) run by another coach, rather than running their own independent stable.
As a coach attached to the stable, he is in charge of training the young wrestlers.
Compound of 部屋付き (heya-tsuki, 'attached to a stable') + の (no, possessive particle) + 親方 (oyakata, 'master/coach'). The term is specific to sumo culture.