Akasaka Blitz
D's hiatus ended in mid 2015. On December 9, 2015, they released a new single "Master Key". This single continues the "Alice in Wonderland" theme that also ran through D's previous single "Happy Unbirthday", which was released in September. D held a tour also named "MASTER KEY" starting from November, they held the tour final at Akasaka Blitz (with the guests: Hello Kitty and My Melody) on December 11.