First Part of Season 3 Airs in July
As announced in their Twitter account, the third season, or likewise called as Idolish7 Third BEAT!, shall be airing starting in July 2021. It was revealed along with the promotional poster.
／— アニメ「アイドリッシュセブン」公式 (@ID7_anime) March 27, 2021
TVアニメシリーズ3期『アイドリッシュセブン Third BEAT!』の第1クールが、2021年7月に放送開始することが決定しました！
公式サイト→https://t.co/772bMqLTOY#アニナナ #アイナナ #アニナナ3期 #7月放送開始 pic.twitter.com/eZV7Lc98g5
Idolish7 (アイドリッシュセブン/IDOLiSH7) is a Japanese rhythm game developed and published by Bandai Namco Online with music collaboration by Lantis for Android and iOS platforms, which first released in Japan on August 20, 2015. The project features character design by Arina Tanemura. Idolish7 has spawned several manga adaptations and novelizations. An anime adaptation by Troyca aired from January to May 2018, and a second season aired from April to December 2020. A third season has been announced. The album Regality connected to the series became the first album credited to a male in-story character group to top the weekly Oricon Albums Chart. (Wikipedia)