主役のリクエスト
 

What's 主役のリクエスト? I think it has to do with birthdays, but I can't determine exactly what it is.

A request made by the main actor in a play/movie/show. Why do you think it has to do with a birthday?

If it came from a context involving a birthday of some sort, then wouldn't 「主役」 in this case mean "the birthday girl/boy"? Since「主役」means "the lead role" and the lead role on a birthday is the person whose birthday it is :p

Perhaps. I'd love to see the context for this. But there's absolutely nothing in OP to suggest that it's about a birthday.

When someone said this on twitter, a lot of replies were talking about a birthday.

When I googled 主役のリクエスト I found lots of pictures of food at birthday parties.

That could be correct. I don't know.