マーダーバタフライ

The popular idol group, PAPILL◇N, rented out an isolated island for their live concert. However, after their concert concludes, their manager is discovered dead outside the venue.
Both the idols and their fans are horrified at this terrifying scene, which completely washes out the dream-like feelings they had before.
As if it were a twist by fate, the weather conditions suddenly take a turn for the worse as well, making it so that it'll take a considerable amount of time for the police to arrive.
So, Sakai Kyou and Yokozimo Koboshi, who happened to be visiting the concert during their vacation decide to take matters into their own hands and investigate who the murderer is.