もし(IF) — 一文から、話が分かれる

"If" is a novel posting service that allows you to write alternative storylines branching off from the middle of a narrative.

First, you write your story in the usual way.
Then, from a sentence where you think "what if something different happened here," you can write another continuation while keeping the original story intact.

No branching settings or programming are necessary. Your completed work can be published in a browser, and readers can follow their chosen storyline as they read.