Mais.7z -

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.

It is highly probable that this refers to one of the following: MAIS.7z

Wikipedia notes that 7-Zip is an open-source tool used for high-ratio file compression. The search results indicate that likely refers to

Files related to a specific community project or mod where "MAIS" is an acronym or title. MAIS.7z

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.