RE:BERSERK is a idol group from the mobile rythm game アイ★チュウ (AiChuu/I-Chu) (for iOS/Android).
Three cute boys suffering from Chuunibyou.
Datenshi Yohane approves.
Lyrics by: http://seigyokus.tumblr.com
I don't own anything. The images used in this song are the Initial GR of the group.