A manga one-shot is complete in one chapter, usually ranging from 16 to over 60 pages long. One-shots are typically created for serialization contests or serve as "new proposals" if the mangaka is already established in the magazine. Some fans of popular series may not realize that many famous manga began as one-shots. Naruto and A Silent Voice are the most prominent examples.
Source：https://www.cbr.com/best-manga-one-shots/
