A simuldub is an English (or other language) dub produced on a near-broadcast schedule, released a few weeks behind the Japanese airing of each episode rather than after the full series ends. It is the dub counterpart to the simulcast.
The simuldub exists to solve a specific queueing problem. Dubbing an episode well takes weeks of translation, adaptation, casting, and recording, so dubbed releases historically trailed the Japanese broadcast by months. Streaming created an audience unwilling to wait, and the simuldub pipeline, first run at scale in the mid 2010s, cut the gap to a few weeks by dubbing episodes while the series is still airing.
That pipeline is an industrial achievement with visible trade-offs. Early simuldub episodes are produced against unfinished materials, scripts may be adjusted as later episodes clarify context, and broadcast versions occasionally differ from later home-video revisions. Fans who track versions learn to ask which release a detail came from.
For this site, dub and sub are both legitimate doors, and neither is treated as a personality. Where a name or line differs between versions, a quiz declares which release it is testing, because an answer that depends on a translation choice must name its translation. Some platforms now experiment with same-day dubs for flagship titles, narrowing the gap further, though the few-weeks rhythm remains the industry norm for a full season slate.
In use"A dub episode arriving three weeks after its Japanese broadcast, while the series is still airing, is a simuldub."