Love Live birthday years (headcanon)
µ's
3rd years - 1996
2nd years - 1997
1st years - 1998
Aqours
3rd years - 1999
2nd years - 2000
1st years - 2001
Nijigasaki
3rd years - 2002
2nd years - 2003
1st years - 2004
Mia is the youngest so she probably born in 2006
Liella
S1 - 1st years (main 5) - 2005
S2 - 1st years (4 new members) - 2006
S3 - 1st years (2 new members) - 2007
Hasunosora
3rd years - 2008
2nd years - 2009
1st years - 2010
Note: Only third years in muse are millenials while most of them are in Gen Z. 1st years in Hasunosora are in Gen Alpha