Monster Strike 2: Senritsu no Lucifer, Tada Hitotsu no Hajimari no Uta

Monster Strike 2 special episode for Golden Week 2017.

"Change the world with music? Foolish." Lucy's world stops after her band disbands. Meaningless days pass, until she meets her cousin Lucifer and his bandmate Ibaraki Doji. They ask her to join their indie band, the "Wicked Pistols". Lucifer talks about his dream of going major after winning the MONSTERS ROCK competition, only for Lucy to reject him outright. However, Lucy's heart begins to thaw after a certain event...

(Source: XFLAG via ANN)