User blog comment:IamJakuhoRaikoben/Chapter 390: The Story of a Boy, Review./@comment-121.54.54.159-20140627133224/@comment-121.54.54.159-20140627133544

Additional info, on Crunchyroll's translation of ch 389, it says Mashima Festival. So I do hope someone can clarify us more about this Mashima/Natsu Festival thing and the Rave script (and the 100 lucky winners).