Japanese idol group Keyakizaka46 participated music festival VIVA LA ROCK EXTRA VIVA LA POP! which was held at Saitama Super Arena on 6 May 2018, without members Hirate Yurina, Imaizumi Yui, Shida Manaka and Harada Aoi. According to the group official web site's explanation: Hirate Yurina absent the festival due to her schedule conflict, Imaizumi Yui suffered from poor health form, Shida Manaka and Harada Aoi are taking hiatus.
Reference: Keyakizaka46's official site
