younger pupil (of the same master); younger disciple; junior member
Refers to a junior disciple under the same teacher or master, often in traditional arts, crafts, or martial arts. Contrasts with 兄弟子 (older disciple).
See also: 兄弟子
He is my younger fellow disciple, studying under the same master.
Looking after the younger disciples is also the role of the senior disciple.