Nijisanji Ark started on March 7, 2021.
There seems to be a large number of participants this time, so they are dividing the start of participation into three stages.
March 7-: Beginners and those who are busy in the second half of the year start participating.
March 12-: Experienced players start participating.
March 16: People who have finished their CR Cup and other events start participating.
See the video below for an explanation of Nijisanji Ark.