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favorite pupil; favourite pupil; teacher's pet
師匠は愛弟子に奥義を伝授した。
The master transmitted the secrets of the art to his favorite pupil.
彼女は茶道の師匠の愛弟子として知られる。
She is known as the tea ceremony master's favorite pupil.
愛弟子が師匠の技を見事に受け継いだ。
The favorite pupil brilliantly inherited the master's skills.