Topic summary
Sidequel
Extracted from the Wikipedia article Spin-off (media).
Sidequels
A spin-off may be called a sidequel, a portmanteau of "side" (as in side-by-side) and "sequel", when it occurs in the same timeframe as the original, sometimes contacting with the main narrative at points. In Japanese, the word gaiden (外伝; pronounced, lit. "outside legends") also refers to such contemporaneous spin-offs and is frequently translated as "side story".