For this new DDR A20 PLUS song update, three new licensed tracks* are available to play starting 3/25/2021 @ 10:00 JST:

I believe what you said / 亜咲花
Realize / 鈴木このみ
思想犯 / ヨルシカ

*North American versions of DDR A20 PLUS will not receive this update

The 9th KAC qualifying songs that you could only get from registering are now unlocked available for regular play.