If you are trying to open this file, you will need a utility like 7-Zip or WinZip to extract its contents and see the "story" inside.

A 7-Zip file containing a visual novel, a game's story assets, or a collection of digital stories.

It is highly probable that this refers to one of the following:

Can you provide about where you saw this name (e.g., a specific website, Discord server, or game modding forum)?

The search results indicate that likely refers to a compressed archive file (with the .7z extension) named "MAIS." However, there is no widely known viral story, game, or cultural phenomenon specifically titled "MAIS.7z" in general public databases.

Wikipedia notes that 7-Zip is an open-source tool used for high-ratio file compression.