1.
side story, spin-off
A supplementary narrative that branches off from a main story, focusing on a secondary character or event. Common in manga, anime, novels, and games.
2.
supplementary biography, unofficial biography
A biographical account covering aspects not included in the official or main biography. The original meaning of the word.
Anecdotes not found in the official history are collected in the supplementary biography.
Usage
In modern usage, sense 1 (side story/spin-off) is far more common than the original biographical meaning. Frequently appears in titles of manga, anime, light novels, and video games.
Etymology
Literally "outside" (外) + "biography/story" (伝). Originally referred to biographical accounts supplementary to the official history.
Common collocations
Related Words
Compare:
本編 (main part)