まゆん (Mayun) is likely a proper noun or a name. Without more context, a direct translation is:
真優ん
However, a more plausible translation could be:
真友
or simply:
まゆん
Given the context that it's an AV title and "まゆん" is likely an actress or a character name, and assuming "まゆん" refers to a person, a more accurate translation is:
真優
The most likely translation is:
真優
這部作品中出演的JAV女優是誰?素人?名字是什麼?