direct disciple; personal pupil
Refers to a student who learns directly under a master, as opposed to an indirect or second-generation student. Often used in traditional arts, crafts, or martial arts contexts.
He is a direct disciple of that famous potter.
師匠は直弟子にしか秘伝を教えなかった。
The master taught the secret techniques only to his direct disciples.
孫弟子 is a disciple of a disciple, i.e., an indirect student, contrasting with 直弟子.
Compound of 直 (direct) and 弟子 (disciple). The reading じき for 直 is a common on'yomi used in compounds meaning 'direct'.