Can you provide about where you saw this name (e.g., a specific website, Discord server, or game modding forum)?
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. Can you provide about where you saw this name (e
A 7-Zip file containing a visual novel, a game's story assets, or a collection of digital stories. a specific website
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.