For "saga" as a long, involved story:
* Brief: A short, concise story.
* Anecdote: A short, amusing or interesting story.
* Summary: A condensed version of a story.
* Epitome: A perfect example or embodiment of something, usually something brief and simple.
For "saga" as a heroic tale of historical events:
* Fable: A short story with a moral lesson, often featuring animals.
* Fairy tale: A fictional story with magical elements.
* Legend: A story passed down through generations, often about heroic deeds.
* Anecdote: A short, amusing or interesting story, often about a specific person or event.
For "saga" as a long period of time with significant events:
* Moment: A short, insignificant period of time.
* Interlude: A brief period of time between two events.
* Epoch: A period of time marked by significant events, but shorter than a saga.
Ultimately, the best antonym for "saga" will depend on the specific context in which you are using it.