A mobile idol-raising simulator and rhythm game with communication events featuring idols and some cards from [[Idolmaster Million Live!|iDOLM@STER Million Live!]].  Idols are sorted into Princess, Fairy, or Angel categories.
Two new idols have been introduced at 765 Pro: [[Shiraishi Tsumugi]] and [[Sakuramori Kaori]]. [[Aoba Misaki]] is also introduced as a second secretary.
It also brings in guest idols like [[Leon_(idolmaster)|]] and [[Shiika_(idolmaster)|]].

See [[Idolmaster Million Live!]] for the list of everyone in Theater Days.

"Official Site":https://millionlive.idolmaster.jp/theaterdays/
アイドルマスターミリオンライブ!シアターデイズ ミリシタ